[jdk21u-dev] RFR: 8339238: Update to use jtreg 7.5.1

[Adam Farley]

Hi all,

This pull request contains a backport of commit [9042aa82](https://github.com/openjdk/jdk25u-dev/commit/9042aa82a890b0f0348ac8127dbd3268f2620346) from the [openjdk/jdk25u-dev](https://github.com/openjdk/jdk25u-dev) repository.

The commit being backported was authored by Christian Stein on 19 Feb 2025 and was reviewed by Erik Joelsson, Jaikiran Pai, Roger Riggs and Iris Clark.

Thanks!

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Commit messages:
 - 8339238: Update to use jtreg 7.5.1

Changes: https://git.openjdk.org/jdk21u-dev/pull/2605/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk21u-dev&pr=2605&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8339238
  Stats: 12 lines in 8 files changed: 0 ins; 0 del; 12 mod
  Patch: https://git.openjdk.org/jdk21u-dev/pull/2605.diff
  Fetch: git fetch https://git.openjdk.org/jdk21u-dev.git pull/2605/head:pull/2605

PR: https://git.openjdk.org/jdk21u-dev/pull/2605