GEODE-7000: Extract reusable rules from GatewayReceiverMetricsTest

[demery-pivotal]

Extract jar-making code from GatewayReceiverMetricsTest into rules for use in other tests:

• SingleFunctionJarRule
• MetricsPublishingServiceJarRule

For all changes:

• Is there a JIRA ticket associated with this PR? Is it referenced in the commit message?

• Has your PR been rebased against the latest commit within the target branch (typically develop)?

• Is your initial contribution a single, squashed commit?

• Does gradlew build run cleanly?

@aaronlindsey Please review

[moleske]

It seems like GEODE-7005 has been filed for the failing test in UnitTestOpenJDK11 (also happened on develop https://concourse.apachegeode-ci.info/teams/main/pipelines/apache-develop-main/jobs/UnitTestOpenJDK8/builds/903

[aaronlindsey]

This was also done in PR #3824, see https://github.com/apache/geode/pull/3824/files#diff-ac14f73a76d33d5c50aca5669b4bbed6

[moleske]

Yeah, I think the idea was to merge this first, but the other PR also got finished around the same time and takes advantage of this extraction

[aaronlindsey]

The version in the other PR is more flexible. It allows creating JARs for any class meant to be used by the service loader. It also doesn't create the JAR for you each test. You have to call createJarFor explicitly. This was done because some tests in the test class don't need the JAR.

[moleske]

Oh I looked at the wrong PR was looking at #3829

[mhansonp]

So, I see some opinions expressed here. Are any of them going to be moved on or should I review this code as it stands?

[demery-pivotal]

This work was concurrently done (and merged) as part of #3824, rendering this PR obsolete.