[jdk17u-dev] RFR: 8293503: gc/metaspace/TestMetaspacePerfCounters.java#Epsilon-64 failed assertGreaterThanOrEqual: expected MMM >= NNN

[SendaoYan]

Hi,
 Backport of JDK-[8293503](https://bugs.openjdk.org/browse/JDK-8293503), to fix the [intermittent failure](https://github.com/openjdk-bots/jdk17u-dev/actions/runs/8841821807/job/24280514750) of TestMetaspacePerfCounters.java.
  This PR add a proper barrier inbetween two measurements. Only change the testcase, the change has been verify on below binary:

- [ ] linux x64 release
- [ ] linux x64 fastdebug
- [ ] linux x86 release
- [ ] linux x86 fastdebug

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Commit messages:
 - Backport 04d7b7d5747d887e12797df8ca3f7608d73d41ff

Changes: https://git.openjdk.org/jdk17u-dev/pull/2431/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk17u-dev&pr=2431&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8293503
  Stats: 196 lines in 1 file changed: 128 ins; 29 del; 39 mod
  Patch: https://git.openjdk.org/jdk17u-dev/pull/2431.diff
  Fetch: git fetch https://git.openjdk.org/jdk17u-dev.git pull/2431/head:pull/2431

PR: https://git.openjdk.org/jdk17u-dev/pull/2431