RFR: 8347124: Clean tests with --enable-linkable-runtime [v3]

[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:
> - [x] 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?

Severin Gehwolf has updated the pull request incrementally with one additional commit since the last revision:

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Changes:
  - all: https://git.openjdk.org/jdk/pull/22969/files
  - new: https://git.openjdk.org/jdk/pull/22969/files/6eceb0de..77dc9376

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=22969&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=22969&range=01-02

  Stats: 8 lines in 2 files changed: 6 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