RFR: 8344197: SM cleanup in java.util.concurrent [v3]

[Roger Riggs]

> Refactored to remove use of doPrivileged() and use of SecurityManager.
> The DefaultForkJoinWorkerThreadFactory no longer uses the SM to target a common thread pool.
> 
> A careful review is requested.

Roger Riggs has updated the pull request incrementally with one additional commit since the last revision:

  Remove additional package access checks in AtomicLongFieldUpdater and AtomicReferenceFieldUpdater

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Changes:
  - all: https://git.openjdk.org/jdk/pull/22119/files
  - new: https://git.openjdk.org/jdk/pull/22119/files/21013c28..9632ac50

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=22119&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=22119&range=01-02

  Stats: 12 lines in 2 files changed: 0 ins; 12 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/22119.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/22119/head:pull/22119

PR: https://git.openjdk.org/jdk/pull/22119