[jdk21] RFR: 8310187: Improve Generational ZGC jtreg testing

Tue Jun 20 11:24:22 UTC 2023

Hi all,

This pull request contains a backport of commit [a0595761](https://github.com/openjdk/jdk/commit/a0595761ef35c4eec8cb84326a869b9473cd5bba) from the [openjdk/jdk](https://git.openjdk.org/jdk) repository.

The commit being backported was authored by Axel Boldt-Christmas on 20 Jun 2023 and was reviewed by Stefan Karlsson, Erik Österlund and Thomas Stuefe.

Thanks!

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Commit messages:
 - Backport a0595761ef35c4eec8cb84326a869b9473cd5bba

Changes: https://git.openjdk.org/jdk21/pull/37/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk21&pr=37&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8310187
  Stats: 619 lines in 70 files changed: 447 ins; 5 del; 167 mod
  Patch: https://git.openjdk.org/jdk21/pull/37.diff
  Fetch: git fetch https://git.openjdk.org/jdk21.git pull/37/head:pull/37

PR: https://git.openjdk.org/jdk21/pull/37