RFR: 8287596: Reorg jdk.test.lib.util.ForceGC [v9]

[Xue-Lei Andrew Fan]

> This is a follow up update per comments in [JDK-8287384 PR](https://urldefense.com/v3/__https://github.com/openjdk/jdk/pull/8907__;!!ACWV5N9M2RV99hQ!O6EQBBr1eLb8OEbyuEwKMh9RY8w0cTN82qBpXMXBQJmWU4FI_-rzbvII5bv3Ipb-i52QkFD41RzdjGKH-huJd-w$ ).  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:

  remove trailing whitespaces

-------------

Changes:
  - all: https://git.openjdk.org/jdk/pull/8979/files
  - new: https://git.openjdk.org/jdk/pull/8979/files/bc51397f..6073acb5

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=8979&range=08
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=8979&range=07-08

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

PR: https://git.openjdk.org/jdk/pull/8979