RFR: 8361349: Fix visibility of CollectedHeap::stop() and ::print_tracing_info()

[Thomas Schatzl]

Hi all,

  please review this refactoring to improve the visibility of `CollectedHeap::stop()` and `CH::print_tracing_info()`.

The change moves these methods to `protected` visibility.

Testing: gha

Thanks,
  Thomas

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Commit messages:
 - 8361349

Changes: https://git.openjdk.org/jdk/pull/26160/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=26160&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8361349
  Stats: 58 lines in 8 files changed: 33 ins; 25 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/26160.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/26160/head:pull/26160

PR: https://git.openjdk.org/jdk/pull/26160