Remove unused imports of ServletException

[Vlatombe]

I'm seeing builds failing due to attempts to load ServletException on agent side when running mvn hpi:run on Kubernetes plugin. Not sure what differs compared to a regular run but in any case, this can be avoided. (similar to jenkinsci/git-plugin#1652)

JUnitParser$ParseResultCallable.invoke creates a
hudson.tasks.junit.TestObject, which imports ServletException for a web method. This can actually be avoided because the exception is unused.

Also removed other usages of this exception which turn out to be unused.

Attached logs for reference

Remote call on JNLP4-connect connection from localhost/[0:0:0:0:0:0:0:1]:55516 failed
[Pipeline] }
[Pipeline] // node
[Pipeline] }
[Pipeline] // retry
[Pipeline] }
[Pipeline] // podTemplate
[Pipeline] End of Pipeline
Also:   hudson.remoting.ProxyException: hudson.remoting.Channel$CallSiteStackTrace: Remote call to JNLP4-connect connection to jenkins.default/10.96.19.40:8001
		at hudson.remoting.Channel.attachCallSiteStackTrace(Channel.java:1923)
		at hudson.remoting.Request.call(Request.java:204)
		at hudson.remoting.RemoteInvocationHandler.invoke(RemoteInvocationHandler.java:312)
		at jdk.proxy2/jdk.proxy2.$Proxy7.fetch(Unknown Source)
		at hudson.remoting.RemoteClassLoader.loadRemoteClass(RemoteClassLoader.java:309)
		at hudson.remoting.RemoteClassLoader.loadWithMultiClassLoader(RemoteClassLoader.java:277)
		at hudson.remoting.RemoteClassLoader.findClass(RemoteClassLoader.java:236)
		at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:593)
		at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:526)
		at PluginClassLoader for junit//hudson.tasks.junit.JUnitParser$ParseResultCallable.invoke(JUnitParser.java:238)
		at Jenkins v2.462.1//hudson.FilePath$FileCallableWrapper.call(FilePath.java:3615)
		at hudson.remoting.UserRequest.perform(UserRequest.java:225)
		at hudson.remoting.UserRequest.perform(UserRequest.java:50)
		at hudson.remoting.Request$2.run(Request.java:391)
		at hudson.remoting.InterceptingExecutorService.lambda$wrap$0(InterceptingExecutorService.java:81)
		at java.base/java.util.concurrent.FutureTask.run(FutureTask.java:317)
		at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1144)
		at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:642)
		at hudson.remoting.Engine$1.lambda$newThread$0(Engine.java:140)
		at java.base/java.lang.Thread.run(Thread.java:1583)
hudson.remoting.ProxyException: java.lang.ClassNotFoundException: javax.servlet.ServletException
	at hudson.remoting.RemoteClassLoader$ClassLoaderProxy.fetch(RemoteClassLoader.java:1029)
	at jdk.internal.reflect.GeneratedMethodAccessor152.invoke(Unknown Source)
	at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.base/java.lang.reflect.Method.invoke(Method.java:568)
	at hudson.remoting.RemoteInvocationHandler$RPCRequest.perform(RemoteInvocationHandler.java:924)
	at hudson.remoting.Request$2.run(Request.java:377)
	at hudson.remoting.InterceptingExecutorService.lambda$wrap$0(InterceptingExecutorService.java:78)
	at org.jenkinsci.remoting.CallableDecorator.call(CallableDecorator.java:18)
	at hudson.remoting.CallableDecoratorList.lambda$applyDecorator$0(CallableDecoratorList.java:19)
	at jenkins.util.ContextResettingExecutorService$2.call(ContextResettingExecutorService.java:46)
	at jenkins.security.ImpersonatingExecutorService$2.call(ImpersonatingExecutorService.java:80)
	at java.base/java.util.concurrent.FutureTask.run$$$capture(FutureTask.java:264)
	at java.base/java.util.concurrent.FutureTask.run(FutureTask.java)
	at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1136)
	at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:635)
	at java.base/java.lang.Thread.run(Thread.java:840)
Also:   hudson.remoting.ProxyException: hudson.remoting.Channel$CallSiteStackTrace: Remote call to JNLP4-connect connection from localhost/[0:0:0:0:0:0:0:1]:55516
		at hudson.remoting.Channel.attachCallSiteStackTrace(Channel.java:1826)
		at hudson.remoting.UserRequest$ExceptionResponse.retrieve(UserRequest.java:356)
		at hudson.remoting.Channel.call(Channel.java:1042)
		at hudson.FilePath.act(FilePath.java:1229)
		at hudson.FilePath.act(FilePath.java:1218)
		at PluginClassLoader for junit//hudson.tasks.junit.JUnitParser.parseResult(JUnitParser.java:146)
		at PluginClassLoader for junit//hudson.tasks.junit.JUnitResultArchiver.parse(JUnitResultArchiver.java:177)
		at PluginClassLoader for junit//hudson.tasks.junit.JUnitResultArchiver.parseAndSummarize(JUnitResultArchiver.java:282)
		at PluginClassLoader for junit//hudson.tasks.junit.pipeline.JUnitResultsStepExecution.run(JUnitResultsStepExecution.java:62)
		at PluginClassLoader for junit//hudson.tasks.junit.pipeline.JUnitResultsStepExecution.run(JUnitResultsStepExecution.java:27)
		at PluginClassLoader for workflow-step-api//org.jenkinsci.plugins.workflow.steps.SynchronousNonBlockingStepExecution.lambda$start$0(SynchronousNonBlockingStepExecution.java:47)
		at java.base/java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:539)
		at java.base/java.util.concurrent.FutureTask.run$$$capture(FutureTask.java:264)
		at java.base/java.util.concurrent.FutureTask.run(FutureTask.java)
		at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1136)
		at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:635)
		at java.base/java.lang.Thread.run(Thread.java:840)
Caused: hudson.remoting.ProxyException: java.lang.NoClassDefFoundError: javax/servlet/ServletException
	at PluginClassLoader for junit//hudson.tasks.junit.JUnitParser$ParseResultCallable.invoke(JUnitParser.java:238)
	at Jenkins v2.462.1//hudson.FilePath$FileCallableWrapper.call(FilePath.java:3615)
	at hudson.remoting.UserRequest.perform(UserRequest.java:225)
	at hudson.remoting.UserRequest.perform(UserRequest.java:50)
	at hudson.remoting.Request$2.run(Request.java:391)
	at hudson.remoting.InterceptingExecutorService.lambda$wrap$0(InterceptingExecutorService.java:81)
	at java.base/java.util.concurrent.FutureTask.run(FutureTask.java:317)
	at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1144)
	at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:642)
	at hudson.remoting.Engine$1.lambda$newThread$0(Engine.java:140)
	at java.base/java.lang.Thread.run(Thread.java:1583)
Also:   hudson.remoting.ProxyException: org.jenkinsci.plugins.workflow.actions.ErrorAction$ErrorId: 8829a6ed-8644-424a-a333-b38043e2c7f7
Caused: hudson.remoting.ProxyException: java.io.IOException: Remote call on JNLP4-connect connection from localhost/[0:0:0:0:0:0:0:1]:55516 failed
	at hudson.remoting.Channel.call(Channel.java:1046)
	at hudson.FilePath.act(FilePath.java:1229)
	at hudson.FilePath.act(FilePath.java:1218)
	at PluginClassLoader for junit//hudson.tasks.junit.JUnitParser.parseResult(JUnitParser.java:146)
	at PluginClassLoader for junit//hudson.tasks.junit.JUnitResultArchiver.parse(JUnitResultArchiver.java:177)
	at PluginClassLoader for junit//hudson.tasks.junit.JUnitResultArchiver.parseAndSummarize(JUnitResultArchiver.java:282)
	at PluginClassLoader for junit//hudson.tasks.junit.pipeline.JUnitResultsStepExecution.run(JUnitResultsStepExecution.java:62)
	at PluginClassLoader for junit//hudson.tasks.junit.pipeline.JUnitResultsStepExecution.run(JUnitResultsStepExecution.java:27)
	at PluginClassLoader for workflow-step-api//org.jenkinsci.plugins.workflow.steps.SynchronousNonBlockingStepExecution.lambda$start$0(SynchronousNonBlockingStepExecution.java:47)
	at java.base/java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:539)
	at java.base/java.util.concurrent.FutureTask.run$$$capture(FutureTask.java:264)
	at java.base/java.util.concurrent.FutureTask.run(FutureTask.java)
	at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1136)
	at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:635)
	at java.base/java.lang.Thread.run(Thread.java:840)

Testing done

Submitter checklist

• Make sure you are opening from a topic/feature/bugfix branch (right side) and not your main branch!
• Ensure that the pull request title represents the desired changelog entry
• Please describe what you did
• Link to relevant issues in GitHub or Jira
• Link to relevant pull requests, esp. upstream and downstream changes
• Ensure you have provided tests - that demonstrates feature works or fixes the issue

[jglick]

Fine though https://issues.jenkins.io/browse/JENKINS-26677 really deserves a durable fix.