[jdk22u] RFR: 8323428: Shenandoah: Unused memory in regions compacted during a full GC should be mangled

[William Kemper]

8323428: Shenandoah: Unused memory in regions compacted during a full GC should be mangled

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Commit messages:
 - Backport a7db4fecebe98135d36c6f46e1fa60959adbe78b

Changes: https://git.openjdk.org/jdk22u/pull/17/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk22u&pr=17&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8323428
  Stats: 3 lines in 1 file changed: 3 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk22u/pull/17.diff
  Fetch: git fetch https://git.openjdk.org/jdk22u.git pull/17/head:pull/17

PR: https://git.openjdk.org/jdk22u/pull/17