[jdk21u-dev] RFR: 8330814: Cleanups for KeepAliveCache tests

[Christoph Langer]

Hi all,

This pull request contains a backport of [JDK-8330814](https://bugs.openjdk.org/browse/JDK-8330814), commit [1e173f9d](https://github.com/openjdk/jdk22u/commit/1e173f9d17e4a42e758217ac98aec4356acac0fa) from the [openjdk/jdk22u](https://git.openjdk.org/jdk22u) repository.

The commit being backported was authored by Christoph Langer on 21 May 2024 and had no reviewers.

Thanks!

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Commit messages:
 - Backport 1e173f9d17e4a42e758217ac98aec4356acac0fa

Changes: https://git.openjdk.org/jdk21u-dev/pull/595/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk21u-dev&pr=595&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8330814
  Stats: 290 lines in 5 files changed: 113 ins; 69 del; 108 mod
  Patch: https://git.openjdk.org/jdk21u-dev/pull/595.diff
  Fetch: git fetch https://git.openjdk.org/jdk21u-dev.git pull/595/head:pull/595

PR: https://git.openjdk.org/jdk21u-dev/pull/595