RFR: 8348829: Remove ObjectMonitor perf counters

[Aleksey Shipilev]

See bug for more discussion. I believe these counters are useless and come with more trouble than their worth.

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Commit messages:
 - Counters removal

Changes: https://git.openjdk.org/jdk/pull/23326/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=23326&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8348829
  Stats: 103 lines in 4 files changed: 0 ins; 102 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/23326.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/23326/head:pull/23326

PR: https://git.openjdk.org/jdk/pull/23326