[jdk21u] RFR: 8314551: More generic way to handshake GC threads with monitor deflation

[Aleksey Shipilev]

Clean backport to to complement [JDK-8307236](https://bugs.openjdk.org/browse/JDK-8307236) that is already in JDK 21. There is no bugtail in JDK 22 so far. Attn @rkennke.

Additional testing:
 - [x] macos-aarch64-server-fastdebug, `hotspot:tier1`

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Commit messages:
 - Backport 31c4e03d5d4682a10825bd7cf2d37971e686b31e

Changes: https://git.openjdk.org/jdk21u/pull/222/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk21u&pr=222&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8314551
  Stats: 3 lines in 1 file changed: 0 ins; 0 del; 3 mod
  Patch: https://git.openjdk.org/jdk21u/pull/222.diff
  Fetch: git fetch https://git.openjdk.org/jdk21u.git pull/222/head:pull/222

PR: https://git.openjdk.org/jdk21u/pull/222