RFR: 8320532: Remove Thread/ThreadGroup suspend/resume

[Alan Bateman]

The deadlock prone Thread/ThreadGroup suspend/resume were deprecated since JDK 1.2, deprecated for removal in Java 14, and re-specified/degraded to throw UnsupportedOperationException unconditionally in Java 19/20.  Early in Java 23 seems a fine time to finally remove these methods.

Corpus analysis of 176 million classes in 485k artifacts found no remaining usages of ThreadGroup.suspend/resume beyond the artifacts that include a copy of java.lang.ThreadGroup (!). It found 87 remaining uses of Thread.suspend and 86 remaining usages of Thread.resume, some of these are tests.

Thread.suspend/resume have always linked to the "Java Thread Primitive Deprecation" page. This originally explained the reasons why suspend/resume were deprecated. When these methods were degraded to throw UOE we changed the text to explain why the ability to suspend or resume a thread was removed. Now we must change it again. One choice is to re-word to explain why the Java APIs were removed or why the Java APIs don't define a way to suspend/resume threads, the other choice (which I prefer) is to remove the text.

The method description of java.lang.management.ThreadInfo.isSuspended is tweaked to link to JVMTI SuspendThread instead of Thread.suspend

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Commit messages:
 - Clarify ThreadInfo.isSuspended
 - Initial commit

Changes: https://git.openjdk.org/jdk/pull/16789/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=16789&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8320532
  Stats: 552 lines in 9 files changed: 116 ins; 430 del; 6 mod
  Patch: https://git.openjdk.org/jdk/pull/16789.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/16789/head:pull/16789

PR: https://git.openjdk.org/jdk/pull/16789