[jdk21u-dev] RFR: 8351484: Race condition in max stats in MonitorList::add

[Francesco Andreuzzi]

Unclean backport of JDK-8351484. Fixes a race condition in `MonitorList::add`. The new test does not pass on `master`. Conflicts were related to the import statements in the test file.

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Commit messages:
 - 8351484: Race condition in max stats in MonitorList::add

Changes: https://git.openjdk.org/jdk21u-dev/pull/1778/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk21u-dev&pr=1778&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8351484
  Stats: 48 lines in 3 files changed: 44 ins; 0 del; 4 mod
  Patch: https://git.openjdk.org/jdk21u-dev/pull/1778.diff
  Fetch: git fetch https://git.openjdk.org/jdk21u-dev.git pull/1778/head:pull/1778

PR: https://git.openjdk.org/jdk21u-dev/pull/1778