RFR: 8324849: Uniform use of synchronizations in NMT

[Afshin Zafari]

In NMT, both `ThreadCritical` and `Tracker` objects are used to do synchronizations. `Tracker` class uses `ThreadCritical` internally and used only for uncommit and release memory operations.  In this change, `Tracker` class is replaced with explicit use of `ThreadCritical` to be the same as the other instances of sync'ing NMT operations.

tiers1-5 tests passed.

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Commit messages:
 - 8324849: Uniform use of synchronizations in NMT

Changes: https://git.openjdk.org/jdk/pull/18000/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=18000&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8324849
  Stats: 73 lines in 7 files changed: 16 ins; 40 del; 17 mod
  Patch: https://git.openjdk.org/jdk/pull/18000.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/18000/head:pull/18000

PR: https://git.openjdk.org/jdk/pull/18000