RFR: 8344773: SM cleanup in ForkJoinPool [v3]

[Doug Lea]

> Complete the SM cleanup in java.util.concurrent that was deferred during other FJP updates

Doug Lea has updated the pull request incrementally with one additional commit since the last revision:

  Reinstate INITIAL_QUEUE_CAPACITY; clarify FJWT javadoc

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Changes:
  - all: https://git.openjdk.org/jdk/pull/22324/files
  - new: https://git.openjdk.org/jdk/pull/22324/files/12126ed1..2a58ea29

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=22324&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=22324&range=01-02

  Stats: 15 lines in 2 files changed: 11 ins; 0 del; 4 mod
  Patch: https://git.openjdk.org/jdk/pull/22324.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/22324/head:pull/22324

PR: https://git.openjdk.org/jdk/pull/22324