chore(templates): Remove Local and Merged template services

[Josh-Matsuoka]

Addresses #351

Since we have the S3 Template service and templates are no longer stored locally there's no longer a need for the local and merged template services. This removes them and the associated test.

[Josh-Matsuoka]

Error: Failed to execute goal org.apache.maven.plugins:maven-compiler-plugin:3.13.0:compile (default-compile) on project cryostat3: Compilation failure
Error: /home/runner/work/cryostat-core/cryostat-core/src/main/java/io/cryostat/jmcagent/JMCAgent.java:[27,45] io.cryostat.core.agent.AgentJMXHelper.ProbeDefinitionException is not public in io.cryostat.core.agent.AgentJMXHelper; cannot be accessed from outside package

This CI failure looks like it needs to be updated to use the recent changes to that classes visibility. I don't think anything in this PR caused that.

[andrewazores]

That's an odd one, but I agree it's not because of this PR. The CI build for this PR's changes on its own passed, but it failed when building cryostat3. It's supposed to do that using the PR contents to check if there are any breaking changes in this PR, but for some reason the cryostat3 build ran into that problem - even though the actual upstream Cryostat 3.0 is already using a recent -core release that has that visibility change.