[jdk11u-dev] RFR: 8330523: Reduce runtime and improve efficiency of KeepAliveTest

[Christoph Langer]

Hi all,

This pull request contains a backport of [JDK-8330523](https://bugs.openjdk.org/browse/JDK-8330523), commit [98038b3d](https://github.com/openjdk/jdk17u-dev/commit/98038b3dfd8984c28a37646de6b1cdaa4c7ae6a3) from the [openjdk/jdk17u-dev](https://git.openjdk.org/jdk17u-dev) repository.

The commit being backported was authored by Christoph Langer on 16 May 2024 and was reviewed by Matthias Baesken.

Thanks!

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Commit messages:
 - Backport 98038b3dfd8984c28a37646de6b1cdaa4c7ae6a3

Changes: https://git.openjdk.org/jdk11u-dev/pull/2888/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk11u-dev&pr=2888&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8330523
  Stats: 1242 lines in 1 file changed: 87 ins; 1023 del; 132 mod
  Patch: https://git.openjdk.org/jdk11u-dev/pull/2888.diff
  Fetch: git fetch https://git.openjdk.org/jdk11u-dev.git pull/2888/head:pull/2888

PR: https://git.openjdk.org/jdk11u-dev/pull/2888