BUILD: Execute RSPEC from JUnit

[original-brownbear]

This makes the RSpecs run from JUnit to:

• Move more logic to Java :P
• Speed up the test run (saves about a minute compared to rake test:core for me)
• Allow for debugging of Java code in Ruby Specs from the IDE
• Allows for moving some test only Java code to the test classpath. Currently, the in memory-serialized queue is the biggest offender here, but there are a few others that needlessly complicate our production code.
• Most importantly: this gives us a starting point for loading Logstash's infrastructure for JUnit tests for Add Stronger Tests to Java Pipeline Execution #8442

This shouldn't change any anything in what the individual rake tasks do since the slow goal was the only one to run Ruby + Java.
This is still the case and I added a new task that can be invoked by the core-java goal and doesn't run the RSpec JUnit invoker.

[jordansissel]

org.logstash.RSpecTests > rspecTests PASSED

Cool beans! Happy to have ./gradlew test be all I need to invoke tests. :)

LGTM

[original-brownbear]

@jordansissel thanks!

[elasticsearch-bot]

Armin Braun merged this into the following branches!

Branch	Commits
6.x	8358260
master	f069eac