RFR: 8347124: Clean tests with --enable-linkable-runtime

[Severin Gehwolf]

Please review this trivial test-only patch in support of running tests on JEP 493 enabled builds. Both tests use the `ToolProvider` API so as to run `jlink` in-process of the test JVM which includes module patches (as in - uses `--patch-module`) which is not supported for JEP 493 enabled JDKs. The proposed fix is to run those two tests in `/othervm` so as to no longer see the module patch of the test JDK.

Testing:
- [ ] GHA
- [x] Affected tests which fail prior the patch and pass after with a JEP 493 enabled JDK. Also tested on a JDK that includes `jmods` folder.

Thoughts?

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Commit messages:
 - 8347124: Clean tests with --enable-linkable-runtime

Changes: https://git.openjdk.org/jdk/pull/22969/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=22969&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8347124
  Stats: 2 lines in 2 files changed: 0 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/jdk/pull/22969.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/22969/head:pull/22969

PR: https://git.openjdk.org/jdk/pull/22969