RFR: 8375620: G1: Convert G1CardTableClaimTable to use Atomic<T>

[Thomas Schatzl]

Hi all,

  please review this change to convert `G1CardTableClaimTable` to use `Atomic<T>`.

Testing: gha,

Thanks,
  Thomas

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Commit messages:
 - 8375620

Changes: https://git.openjdk.org/jdk/pull/29297/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=29297&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8375620
  Stats: 13 lines in 3 files changed: 1 ins; 1 del; 11 mod
  Patch: https://git.openjdk.org/jdk/pull/29297.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/29297/head:pull/29297

PR: https://git.openjdk.org/jdk/pull/29297