RFR: 8325503: Add GC specific prefix for CheckForUnmarked related classes

[Albert Mingkun Yang]

Add prefix some generic class names used for young-gc card verification.

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Commit messages:
 - prefix-rename

Changes: https://git.openjdk.org/jdk/pull/17774/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=17774&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8325503
  Stats: 9 lines in 2 files changed: 0 ins; 0 del; 9 mod
  Patch: https://git.openjdk.org/jdk/pull/17774.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/17774/head:pull/17774

PR: https://git.openjdk.org/jdk/pull/17774