[jdk21u] RFR: 8315937: Enable parallelism in vmTestbase/nsk/stress/numeric tests

[Soumadipta Roy]

Backporting the fix for https://bugs.openjdk.org/browse/JDK-8315937 merged as part of https://github.com/openjdk/jdk/pull/15725. https://github.com/openjdk/jdk/commit/eb1f67b160c4d2b8feb7330786ecd8e53ed53946.patch could be applied cleanly.

Below are the results:
* before_release: **117.84s user 10.43s system 685% cpu 18.725 total**
* before_fastdebug: **375.61s user 13.10s system 838% cpu 46.382 total**
* after_release: **119.35s user 11.63s system 728% cpu 17.991 total**
* after_fastdebug: **381.47s user 13.07s system 857% cpu 46.003 total**

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Commit messages:
 - Backport 339034c150cad7d3e1df55dbfac6c2b7746c4f92

Changes: https://git.openjdk.org/jdk21u/pull/212/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk21u&pr=212&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8315937
  Stats: 24 lines in 1 file changed: 0 ins; 24 del; 0 mod
  Patch: https://git.openjdk.org/jdk21u/pull/212.diff
  Fetch: git fetch https://git.openjdk.org/jdk21u.git pull/212/head:pull/212

PR: https://git.openjdk.org/jdk21u/pull/212