RFR: 8289137: Automatically adapt Young/OldPLABSize and when setting only MinTLABSize

[Thomas Schatzl]

Hi all,

  can I get reviews for this enhancement fixing a sometimes annoying UI issue where setting `-XX:MinTLABSize` does not automatically update `-XX:YoungPLABSize` and `-XX:OldPLABSize` if they are not set?
This avoids some unnecessary retries.

Testing: gha, test case

Thanks,
  Thomas

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Commit messages:
 - Add test
 - initial version

Changes: https://git.openjdk.org/jdk/pull/9425/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=9425&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8289137
  Stats: 93 lines in 4 files changed: 93 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/9425.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/9425/head:pull/9425

PR: https://git.openjdk.org/jdk/pull/9425