RFR: JDK-8319300: Remove unused methods in WorkArounds and Utils

[Hannes Wallnöfer]

Please review a simple removal of unused methods in `WorkArounds` and `Utils`. 

`Utils.findClass(Element,String)` was the principal entry point of this cluster of methods. It was last used by the `ThrowsTaglet` `inherit` method, but that code was removed in JDK-8295277.

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Commit messages:
 - JDK-8319300: Remove unused methods in WorkArounds and Utils

Changes: https://git.openjdk.org/jdk/pull/16472/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=16472&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8319300
  Stats: 111 lines in 2 files changed: 0 ins; 111 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/16472.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/16472/head:pull/16472

PR: https://git.openjdk.org/jdk/pull/16472