RFR: 8320786: Remove ThreadGroup.stop [v2]

[Alan Bateman]

> ThreadGroup.stop was deprecated since JDK 1.2, deprecated for removal in Java 18, and re-specified/degraded to throw UnsupportedOperationException unconditionally in Java 20. Early in Java 23 seems a fine time to finally remove this method. Corpus analysis of 176 million classes in 485k artifacts found residual usages in 14 artifacts, so not many.
> 
> It would be nice if we could remove Thread.stop at the same time. Sadly there are still quite a few artifacts containing code (and in some cases tests) that reference this method. We will have to come back to this in some future release.

Alan Bateman has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains two commits:

 - Merge
 - Initial commit

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Changes: https://git.openjdk.org/jdk/pull/16828/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=16828&range=01
  Stats: 17 lines in 2 files changed: 0 ins; 17 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/16828.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/16828/head:pull/16828

PR: https://git.openjdk.org/jdk/pull/16828