issues/392 TCK challenge for adding support for running Concurrency 3.0 TCK signature tests on Java 21

[scottmarlow]

For addressing the https://github.com/jakartaee/concurrency/issues/392 challenge if that is accepted.

This change is equivalent to https://github.com/jakartaee/platform-tck/pull/1206. I locally tested the https://github.com/jakartaee/platform-tck/pull/1206 change but have not yet tested this pull request. I will test this pull request locally as well if the Concurrency https://github.com/jakartaee/concurrency/issues/392 challenge is accepted and after local testing of the fix, will then mark this pull request as ready.