RFR: 8341042: GenShen: Reset mark bitmaps for unaffiliated regions when preparing for a cycle

[William Kemper]

Conflict with whitespace change.

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Commit messages:
 - Backport 988b98bb4964e15391a1f1a40d984c91480f1ccb

Changes: https://git.openjdk.org/shenandoah-jdk21u/pull/107/files
  Webrev: https://webrevs.openjdk.org/?repo=shenandoah-jdk21u&pr=107&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8341042
  Stats: 6 lines in 2 files changed: 1 ins; 4 del; 1 mod
  Patch: https://git.openjdk.org/shenandoah-jdk21u/pull/107.diff
  Fetch: git fetch https://git.openjdk.org/shenandoah-jdk21u.git pull/107/head:pull/107

PR: https://git.openjdk.org/shenandoah-jdk21u/pull/107