[jdk11u-dev] 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.

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

Commit messages:
 - Backport cee44a625594fd805a05c4a69033eb677a5a6f17

Changes: https://git.openjdk.org/jdk11u-dev/pull/2437/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk11u-dev&pr=2437&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/jdk11u-dev/pull/2437.diff
  Fetch: git fetch https://git.openjdk.org/jdk11u-dev.git pull/2437/head:pull/2437

PR: https://git.openjdk.org/jdk11u-dev/pull/2437