RFR: 8333035: Parallel: Remove ParMarkBitMap::IterationStatus

[Albert Mingkun Yang]

Trivial removing effectively dead code.

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Commit messages:
 - pgc-return-void

Changes: https://git.openjdk.org/jdk/pull/19419/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=19419&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8333035
  Stats: 11 lines in 3 files changed: 0 ins; 8 del; 3 mod
  Patch: https://git.openjdk.org/jdk/pull/19419.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/19419/head:pull/19419

PR: https://git.openjdk.org/jdk/pull/19419