RFR: 8346929: runtime/ClassUnload/DictionaryDependsTest.java fails with "Test failed: should be unloaded" [v3]

[Coleen Phillimore]

> Adopt the new ClassUnloadCommon.triggerUnloading API to make the unloading tests more reliable.
> Tested with tier1 on all platforms.

Coleen Phillimore has updated the pull request incrementally with one additional commit since the last revision:

  Add @dholmes-ora comments.

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Changes:
  - all: https://git.openjdk.org/jdk/pull/22974/files
  - new: https://git.openjdk.org/jdk/pull/22974/files/e5e85aa9..a8ed23ec

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=22974&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=22974&range=01-02

  Stats: 3 lines in 3 files changed: 0 ins; 3 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/22974.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/22974/head:pull/22974

PR: https://git.openjdk.org/jdk/pull/22974