[jdk21u-dev] RFR: 8328168: Epsilon: Premature OOM when allocating object larger than uncommitted heap size

[Aleksey Shipilev]

Fixes Epsilon performance problem, corner-case with clear test.

Additional testing:
 - [x] MacOS AArch64 server fastdebug, new regression test fails without the patch, passes with it
 - [x] MacOS AArch64 server fastdebug, `gc/epsilon`

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Commit messages:
 - Backport 7baec6622254fc21e315b974a213605a7605daac

Changes: https://git.openjdk.org/jdk21u-dev/pull/518/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk21u-dev&pr=518&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8328168
  Stats: 51 lines in 2 files changed: 47 ins; 0 del; 4 mod
  Patch: https://git.openjdk.org/jdk21u-dev/pull/518.diff
  Fetch: git fetch https://git.openjdk.org/jdk21u-dev.git pull/518/head:pull/518

PR: https://git.openjdk.org/jdk21u-dev/pull/518