RFR: 8340137: GenShen: Reset mark bitmaps when a region is recycled

[William Kemper]

Clean back port, critical bug fix.

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Commit messages:
 - Backport a8e2908eed1ab8c271eb206e0a41ee3d38b18de3

Changes: https://git.openjdk.org/shenandoah-jdk21u/pull/103/files
  Webrev: https://webrevs.openjdk.org/?repo=shenandoah-jdk21u&pr=103&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8340137
  Stats: 4 lines in 1 file changed: 4 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/shenandoah-jdk21u/pull/103.diff
  Fetch: git fetch https://git.openjdk.org/shenandoah-jdk21u.git pull/103/head:pull/103

PR: https://git.openjdk.org/shenandoah-jdk21u/pull/103