RFR: 8338564: Remove obsolete AbstractNamedEntry::equals method

[Adam Sotona]

Method `jdk.internal.classfile.impl.AbstractPoolEntry.AbstractNamedEntry::equals` implementation is invalid.
Fortunately it is overridden with valid implementation in all its sub types and it can be removed.

This patch removes the obsolete an invalid method implementation.

Please review.

Thanks,
Adam

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Commit messages:
 - 8338564: Remove obsolete AbstractNamedEntry::equals method

Changes: https://git.openjdk.org/jdk/pull/20622/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=20622&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8338564
  Stats: 9 lines in 1 file changed: 0 ins; 9 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/20622.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/20622/head:pull/20622

PR: https://git.openjdk.org/jdk/pull/20622