RFR: 7904129: Update jtreg to bundle JUnit 5.14.2

[Christian Stein]

Please review this change updating the JUnit version to [5.14.2](https://docs.junit.org/5.14.2/release-notes.html).

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Commit messages:
 - 7904129: Update jtreg to bundle JUnit 5.14.2

Changes: https://git.openjdk.org/jtreg/pull/306/files
  Webrev: https://webrevs.openjdk.org/?repo=jtreg&pr=306&range=00
  Issue: https://bugs.openjdk.org/browse/CODETOOLS-7904129
  Stats: 5 lines in 2 files changed: 1 ins; 0 del; 4 mod
  Patch: https://git.openjdk.org/jtreg/pull/306.diff
  Fetch: git fetch https://git.openjdk.org/jtreg.git pull/306/head:pull/306

PR: https://git.openjdk.org/jtreg/pull/306