RFR: 7903999: Release jtreg 7.5.2

[Christian Stein]

Please review this change preparing the `7.5.2` release of jtreg.

The version number `7.6` will be restored on the main branch after the release; a dedidated `7.5.x` branch is not required, yet.

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Commit messages:
 - 7903999: Release jtreg 7.5.2

Changes: https://git.openjdk.org/jtreg/pull/263/files
  Webrev: https://webrevs.openjdk.org/?repo=jtreg&pr=263&range=00
  Issue: https://bugs.openjdk.org/browse/CODETOOLS-7903999
  Stats: 15 lines in 2 files changed: 13 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/jtreg/pull/263.diff
  Fetch: git fetch https://git.openjdk.org/jtreg.git pull/263/head:pull/263

PR: https://git.openjdk.org/jtreg/pull/263