RFR: 8323023: GenShen: Region logging test fails intermittently

[William Kemper]

This test used to exercise a specific Shenandoah feature, but we've long since rewritten that feature to be based on unified logging. The test doesn't need to retest unified logging features.

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Commit messages:
 - Do not re-test unified logging features

Changes: https://git.openjdk.org/shenandoah/pull/380/files
 Webrev: https://webrevs.openjdk.org/?repo=shenandoah&pr=380&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8323023
  Stats: 131 lines in 2 files changed: 57 ins; 74 del; 0 mod
  Patch: https://git.openjdk.org/shenandoah/pull/380.diff
  Fetch: git fetch https://git.openjdk.org/shenandoah.git pull/380/head:pull/380

PR: https://git.openjdk.org/shenandoah/pull/380