RFR: 8346929: runtime/ClassUnload/DictionaryDependsTest.java fails with "Test failed: should be unloaded" [v2]

[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:

  Fixed @calvincheung comments.

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Changes:
  - all: https://git.openjdk.org/jdk/pull/22974/files
  - new: https://git.openjdk.org/jdk/pull/22974/files/fdbbda40..e5e85aa9

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=22974&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=22974&range=00-01

  Stats: 2 lines in 2 files changed: 0 ins; 1 del; 1 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