RFR: 8284965: closed test sun/java2d/OpenGL/XORPaint.java is unstable

[Phil Race]

This fix moves a closed test to open but updated to be more comprehensive in testing multiple pipelines and with some stabilisation improvements.

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Commit messages:
 - 8284965

Changes: https://git.openjdk.java.net/jdk/pull/8345/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=8345&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8284965
  Stats: 239 lines in 1 file changed: 239 ins; 0 del; 0 mod
  Patch: https://git.openjdk.java.net/jdk/pull/8345.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/8345/head:pull/8345

PR: https://git.openjdk.java.net/jdk/pull/8345