[jdk23u] RFR: 8336914: Shenandoah: Missing verification steps after JDK-8255765

[William Kemper]

Clean backport. Restores a long lost verification step.

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Commit messages:
 - Backport e51e40c2b9f51d012c01407e0b8dadaab464753e

Changes: https://git.openjdk.org/jdk23u/pull/180/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk23u&pr=180&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8336914
  Stats: 4 lines in 1 file changed: 3 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk23u/pull/180.diff
  Fetch: git fetch https://git.openjdk.org/jdk23u.git pull/180/head:pull/180

PR: https://git.openjdk.org/jdk23u/pull/180