[jdk21u] RFR: 8318608: Enable parallelism in vmTestbase/nsk/stress/threads tests

[Elif Aslan]

Clean backport to enable parallelism in vmTestbase/nsk/stress/threads tests.

Tested with GHA.

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Commit messages:
 - Backport cee44a625594fd805a05c4a69033eb677a5a6f17

Changes: https://git.openjdk.org/jdk21u/pull/430/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk21u&pr=430&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8318608
  Stats: 24 lines in 1 file changed: 0 ins; 24 del; 0 mod
  Patch: https://git.openjdk.org/jdk21u/pull/430.diff
  Fetch: git fetch https://git.openjdk.org/jdk21u.git pull/430/head:pull/430

PR: https://git.openjdk.org/jdk21u/pull/430