Suspend distribution of Crowd2 plugin (jenkins-infra#755)

* Suspend Crowd2 plugin distribution - uses closed source dependency

jenkins-infra/helpdesk#3854 explains that
the Crowd2 integration plugin uses a dependency that is not open source
licensed.

The Crowd2 integration library is Atlassian licensed as described in
jenkins-infra/helpdesk#3842 (comment)

The Atlassian license is not an open source license.  Refer to
https://www.atlassian.com/legal/software-license-agreement for the
details of the license.

https://www.jenkins.io/project/governance/#license says that the Jenkins
project requires plugins that it distributes to be open source, including
their dependencies.  When a closed source dependency is detected in a
plugin, we suspend distribution of that plugin.  If maintainers update
the plugin to remove the closed source dependency, distribution can
begin for the new release that removes the closed source dependency.

Fixes jenkins-infra/helpdesk#3854

* Better comment phrase

* Reduce diffs

resources/artifact-ignores.properties

@@ -887,3 +887,11 @@ batch-task@1.16               # SECURITY-1025
 batch-task@1.17               # SECURITY-1025
 batch-task@1.18               # SECURITY-1025
 batch-task@1.19               # SECURITY-1025
+
+# Non-open source dependency, refer to:
+#   https://github.com/jenkins-infra/helpdesk/issues/3854
+#   https://github.com/jenkins-infra/helpdesk/issues/3842#issuecomment-1839385370
+#   https://github.com/jenkins-infra/helpdesk/issues/3842#issuecomment-1841569022
+#   https://github.com/jenkins-infra/helpdesk/issues/3842#issuecomment-1847399101
+#   https://github.com/jenkins-infra/helpdesk/issues/3842#issuecomment-1847559631
+crowd2 = https://github.com/jenkins-infra/helpdesk/issues/3854