RFR: 8331516: Tests should not use the "Classpath" exception form of the legal header

[Phil Race]

Change GPL+CP -> GPL as required for all tests.

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Commit messages:
 - 8331516

Changes: https://git.openjdk.org/jdk/pull/19068/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=19068&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8331516
  Stats: 4 lines in 1 file changed: 0 ins; 2 del; 2 mod
  Patch: https://git.openjdk.org/jdk/pull/19068.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/19068/head:pull/19068

PR: https://git.openjdk.org/jdk/pull/19068