RFR: 8370804: G1: Make G1HeapRegionAttr::remset_is_tracked() conform to coding style

[Thomas Schatzl]

Hi all,

  please fix several places where the `remset_is_tracked` getter and related identifiers do not fit hotspot style, recommending the verb as first part.

Testing: gha

(Please note the dependency on #28038)

Thanks,
  Thomas

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Depends on: https://git.openjdk.org/jdk/pull/28038

Commit messages:
 - 8370804

Changes: https://git.openjdk.org/jdk/pull/28039/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=28039&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8370804
  Stats: 26 lines in 6 files changed: 0 ins; 0 del; 26 mod
  Patch: https://git.openjdk.org/jdk/pull/28039.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/28039/head:pull/28039

PR: https://git.openjdk.org/jdk/pull/28039