RFR: 8310183: Update GitHub Actions to use boot JDK for building jtreg

[Christian Stein]

Please review this change to use the boot JDK for building jtreg when running on GitHub Actions.

This is a best-effort follow-up change to
- #14448
which didn't have the desired results - the `Bad address` error does still appear with using the pre-installed JDKs 11 and 17.

Tests using the boot JDK for building jtreg seem to be successful and more stable.

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Commit messages:
 - Fix syntax
 - Use real path to boot JDK
 - Install Oracle JDK 17 to build jtreg
 - Build with default JDK
 - Use boot JDK to build jtreg
 - Prevent Bad address error in MSYS

Changes: https://git.openjdk.org/jdk/pull/14507/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=14507&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8310183
  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/14507.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/14507/head:pull/14507

PR: https://git.openjdk.org/jdk/pull/14507