RFR: 8336915: Shenandoah: Remove unused ShenandoahVerifier::verify_after_evacuation

[Satyen Subramaniam]

Removing the `verify_after_evacuation()` function, since last use was removed in [JDK-8240868](https://bugs.openjdk.org/browse/JDK-8240868) as directed by [JDK-8336915](https://bugs.openjdk.org/browse/JDK-8336915)

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Commit messages:
 - Removing verify_after_evacuation()

Changes: https://git.openjdk.org/jdk/pull/20365/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=20365&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8336915
  Stats: 13 lines in 2 files changed: 0 ins; 13 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/20365.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/20365/head:pull/20365

PR: https://git.openjdk.org/jdk/pull/20365