[jdk11u-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: 1553.74s user 152.18s system 426% cpu 6:39.56 total
after: 1593.15s user 149.07s system 1610% cpu 1:48.17 total

Release
before: 1522.79s user 292.63s system 508% cpu 5:56.78 total
after: 1579.50s user 246.10s system 2069% cpu 1:28.21 total

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Commit messages:
 - Backport 003e86fe38ca1b809418f6282336e259862d0776

Changes: https://git.openjdk.org/jdk11u-dev/pull/2762/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk11u-dev&pr=2762&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8324755
  Stats: 115 lines in 6 files changed: 0 ins; 115 del; 0 mod
  Patch: https://git.openjdk.org/jdk11u-dev/pull/2762.diff
  Fetch: git fetch https://git.openjdk.org/jdk11u-dev.git pull/2762/head:pull/2762

PR: https://git.openjdk.org/jdk11u-dev/pull/2762