[jdk21u] RFR: 8314495: Update to use jtreg 7.3.1

[Aleksey Shipilev]

Unclean backport to bring jtreg version in alignment with mainline. The uncleanliness comes from contextual difference re gtest version in the adjacent hunks.

Additional testing:
 - [ ] GHA

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Depends on: https://git.openjdk.org/jdk21u/pull/122

Commit messages:
 - Backport c50315de8f13d316a7de08be53716cd88fa801c4

Changes: https://git.openjdk.org/jdk21u/pull/123/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk21u&pr=123&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8314495
  Stats: 9 lines in 8 files changed: 0 ins; 0 del; 9 mod
  Patch: https://git.openjdk.org/jdk21u/pull/123.diff
  Fetch: git fetch https://git.openjdk.org/jdk21u.git pull/123/head:pull/123

PR: https://git.openjdk.org/jdk21u/pull/123