[jdk21u] RFR: 8314426: runtime/os/TestTrimNative.java is failing on slow machines

[Aleksey Shipilev]

Clean backport to stabilize the test.

Additional testing:
 - [x] 100+ repetitions of affected test

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Commit messages:
 - Backport 20e94784c9f7c30e95550c72aedb5e986a153114

Changes: https://git.openjdk.org/jdk21u/pull/86/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk21u&pr=86&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8314426
  Stats: 6 lines in 1 file changed: 3 ins; 1 del; 2 mod
  Patch: https://git.openjdk.org/jdk21u/pull/86.diff
  Fetch: git fetch https://git.openjdk.org/jdk21u.git pull/86/head:pull/86

PR: https://git.openjdk.org/jdk21u/pull/86