RFR: 8287596: Reorg jdk.test.lib.util.ForceGC

[Mandy Chung]

On Wed, 1 Jun 2022 19:08:03 GMT, Xue-Lei Andrew Fan <xuelei at openjdk.org> wrote:

> This is a follow up update per comments in [JDK-8287384 PR](https://github.com/openjdk/jdk/pull/8907).  The tier1 and tier2 test in open part looks good to me.  Please help to run Mach5 just case the closed test cases are impacted.

JDK-8287384 causes `test/jdk/java/lang/invoke/defineHiddenClass/UnloadingTest.java` to timeout when running with fastdebug VM.  I think this might be caused by more frequent GCs.

I tried your patch and the test fails.

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PR: https://git.openjdk.java.net/jdk/pull/8979