[jdk21u-dev] RFR: 8324755: Enable parallelism in vmTestbase/gc/gctests/LargeObjects tests

[Soumadipta Roy]

Backporting the fix for https://bugs.openjdk.org/browse/JDK-8324755 merged as part of openjdk/jdk#18798. 
https://github.com/openjdk/jdk/commit/003e86fe38ca1b809418f6282336e259862d0776.patch could be applied cleanly.

Run details on AL2_x86_64:

Fastdebug
before: 2386.48s user 64.68s system 147% cpu 27:38.98 total
after: 2562.90s user 57.62s system 589% cpu 7:24.18 total

Release
before: 1064.85s user 51.97s system 123% cpu 15:02.09 total
after: 1073.77s user 52.81s system 479% cpu 3:54.78 total

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Commit messages:
 - Backport 003e86fe38ca1b809418f6282336e259862d0776

Changes: https://git.openjdk.org/jdk21u-dev/pull/684/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk21u-dev&pr=684&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8324755
  Stats: 115 lines in 5 files changed: 0 ins; 115 del; 0 mod
  Patch: https://git.openjdk.org/jdk21u-dev/pull/684.diff
  Fetch: git fetch https://git.openjdk.org/jdk21u-dev.git pull/684/head:pull/684

PR: https://git.openjdk.org/jdk21u-dev/pull/684