[jdk21u-dev] RFR: 8321940: Improve CDSHeapVerifier in handling of interned strings

[Ben Taylor]

Clean backport of a change to fix a false-positive error condition in the cdsHeapVerifier. 
This change also reduces the number of manually curated `ADD_EXCL` entries in cdsHeapVerifier, improving long-term maintainability.

Change passes tier 1 tests locally on x86_64 linux.

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Commit messages:
 - Backport 4f3de09672d203a0182f330645962c3d08e5e206

Changes: https://git.openjdk.org/jdk21u-dev/pull/925/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk21u-dev&pr=925&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8321940
  Stats: 36 lines in 1 file changed: 6 ins; 30 del; 0 mod
  Patch: https://git.openjdk.org/jdk21u-dev/pull/925.diff
  Fetch: git fetch https://git.openjdk.org/jdk21u-dev.git pull/925/head:pull/925

PR: https://git.openjdk.org/jdk21u-dev/pull/925