RFR: 8354541: Remove Shenandoah post barrier expand loop opts

[William Kemper]

Conflict in file missing from 21.

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Commit messages:
 - 8354541: Remove Shenandoah post barrier expand loop opts

Changes: https://git.openjdk.org/shenandoah-jdk21u/pull/192/files
  Webrev: https://webrevs.openjdk.org/?repo=shenandoah-jdk21u&pr=192&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8354541
  Stats: 250 lines in 5 files changed: 0 ins; 248 del; 2 mod
  Patch: https://git.openjdk.org/shenandoah-jdk21u/pull/192.diff
  Fetch: git fetch https://git.openjdk.org/shenandoah-jdk21u.git pull/192/head:pull/192

PR: https://git.openjdk.org/shenandoah-jdk21u/pull/192