RFR: JDK-8289798: Update to use jtreg 7

[Christian Stein]

Please review the change to update to using jtreg 7.

The primary change is to the `jib-profiles.js` file, which specifies the version of jtreg to use, for those systems that rely on this file. In addition, the `requiredVersion` has been updated in the various `TEST.ROOT` files.

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Commit messages:
 - Merge branch 'openjdk:master' into JDK-8289798-jtreg-7
 - Update to new JUnit JAR file
 - Merge branch 'openjdk:master' into JDK-8289798-jtreg-7
 - Merge branch 'openjdk:master' into JDK-8289798-jtreg-7
 - Merge branch 'openjdk:master' into JDK-8289798-jtreg-7
 - Merge branch 'openjdk:master' into JDK-8289798-jtreg-7
 - Update github-actions.conf
 - JDK-8289798: Update to use jtreg 7

Changes: https://git.openjdk.org/jdk/pull/9393/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=9393&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8289798
  Stats: 11 lines in 8 files changed: 0 ins; 0 del; 11 mod
  Patch: https://git.openjdk.org/jdk/pull/9393.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/9393/head:pull/9393

PR: https://git.openjdk.org/jdk/pull/9393