RFR: 8287596: Reorg jdk.test.lib.util.ForceGC [v2]

[Xue-Lei Andrew Fan]

> 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.

Xue-Lei Andrew Fan has updated the pull request incrementally with one additional commit since the last revision:

  back to wait 1 second

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Changes:
  - all: https://git.openjdk.java.net/jdk/pull/8979/files
  - new: https://git.openjdk.java.net/jdk/pull/8979/files/a1d91596..f3d9eb82

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=8979&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=8979&range=00-01

  Stats: 2 lines in 1 file changed: 0 ins; 0 del; 2 mod
  Patch: https://git.openjdk.java.net/jdk/pull/8979.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/8979/head:pull/8979

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