[jdk18u] RFR: 8278065: Refactor subclassAudits to use ClassValue

[Roman Kennke]

This backports the fix for JDK-8278065, which fixes a number of small issues with the preceding change for JDK-8277072.
The original change has baked for several weeks in jdk19 and applies cleanly.

Testing:
 - [ ] tier1
 - [ ] tier2
 - [ ] tier3

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

Depends on: https://git.openjdk.java.net/jdk18u/pull/36

Commit messages:
 - Backport 8fed8ab29cae4f189f44609c23f116967eef6bdf

Changes: https://git.openjdk.java.net/jdk18u/pull/50/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk18u&pr=50&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8278065
  Stats: 105 lines in 3 files changed: 2 ins; 89 del; 14 mod
  Patch: https://git.openjdk.java.net/jdk18u/pull/50.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk18u pull/50/head:pull/50

PR: https://git.openjdk.java.net/jdk18u/pull/50