[jdk16] RFR: 8258259: Unicode linebreak matching behavior is incorrect; backout JDK-8235812

[Stuart Marks]

Back out code changes from JDK-8235812 to restore correct matching behavior. Adjust test to comment out cases that tested for incorrect behavior.

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Commit messages:
 - 8258259: Unicode linebreak matching behavior is incorrect; backout JDK-8235812

Changes: https://git.openjdk.java.net/jdk16/pull/40/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk16&pr=40&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8258259
  Stats: 85 lines in 2 files changed: 8 ins; 56 del; 21 mod
  Patch: https://git.openjdk.java.net/jdk16/pull/40.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk16 pull/40/head:pull/40

PR: https://git.openjdk.java.net/jdk16/pull/40