spark-3.5: add openjdk-21 support

[mark-thm]

Fixes:

Related: https://github.com/wolfi-dev/os/pull/26803

#26803 failed to include jdk21 support because it's not strictly documented. In reality, Spark runs fine on jdk21 (and the new tests added in the PR should demonstrate that). Unfortunately, #26803 now forces inclusion of some jdk so realistically it should allow for additional, valid jdks.