RFR: 8306135: Clean up and open source some AWT tests

[Alexander Zuev]

Cleaning up and open sourcing three AWT tests

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Commit messages:
 - 8306135: Clean up and open source some AWT tests

Changes: https://git.openjdk.org/jdk/pull/13518/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=13518&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8306135
  Stats: 355 lines in 3 files changed: 355 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/13518.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/13518/head:pull/13518

PR: https://git.openjdk.org/jdk/pull/13518