RFR: 8290023: Remove use of IgnoreUnrecognizedVMOptions in gc tests

[Thomas Schatzl]

Hi all,

  can I have reviews for removal of the use of `-XX:+IgnoreUnrecognizedVMOptions` for gc tests?

As per [JDK-8228493](https://bugs.openjdk.org/browse/JDK-8228493) use of that option has drawbacks wrt to test reliability, so trying to remove them by
* duplicating `@test` blocks (mostly sme Shenandoah tests as I could not find a good way for them)
* adding additional `@requires`
* removing it in tests where it is not actually required

Testing: gha, running tests

Thanks,
  Thomas

-------------

Commit messages:
 - Merge branch 'master' into 8290023-remove-use-of-ignoreunrecognized
 - fix test
 - Merge fixes
 - Initial batch

Changes: https://git.openjdk.org/jdk/pull/9443/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=9443&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8290023
  Stats: 258 lines in 13 files changed: 189 ins; 26 del; 43 mod
  Patch: https://git.openjdk.org/jdk/pull/9443.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/9443/head:pull/9443

PR: https://git.openjdk.org/jdk/pull/9443