RFR: 8305994: Guarantee eventual async monitor deflation

Fri Apr 14 10:59:45 UTC 2023

See discussion in the bug. This PR introduces a safety rail that kicks in when the threshold heuristics fails, and it is cleanly backportable to JDK 17, where the problem manifests as apparent memory leak. There are other options to resolve this (see the bug), but I think this one is the easiest in the interim. 

Additional testing:
 - [ ] Linux x86_64 `tier1`
 - [ ] Linux x86_64 `tier2`
 - [x] `runtime/Monitor` tests
 - [x] Ad-hoc experiments (see example in the bug)
 - [x] New feature test

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Commit messages:
 - Copyright updates
 - Touchup the option description
 - Test and some modifications
 - GuaranteedAsyncDeflationInterval

Changes: https://git.openjdk.org/jdk/pull/13474/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=13474&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8305994
  Stats: 196 lines in 4 files changed: 191 ins; 2 del; 3 mod
  Patch: https://git.openjdk.org/jdk/pull/13474.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/13474/head:pull/13474

PR: https://git.openjdk.org/jdk/pull/13474