[jdk17u-dev] RFR: 8293872: Make runtime/Thread/ThreadCountLimit.java more robust

[Elif Aslan]

Clean backport to Make runtime/Thread/ThreadCountLimit.java more robust.
GHA tested

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Commit messages:
 - Backport 36b61c5d7e7732924f494fa24c0e286e41279fc3

Changes: https://git.openjdk.org/jdk17u-dev/pull/2614/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk17u-dev&pr=2614&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8293872
  Stats: 49 lines in 1 file changed: 21 ins; 18 del; 10 mod
  Patch: https://git.openjdk.org/jdk17u-dev/pull/2614.diff
  Fetch: git fetch https://git.openjdk.org/jdk17u-dev.git pull/2614/head:pull/2614

PR: https://git.openjdk.org/jdk17u-dev/pull/2614