RFR: 8315600: Open source few more headless Swing misc tests

[Prasanta Sadhukhan]

Few more closed swing headless tests are opensourced

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Commit messages:
 - 8315600: Open source few more headless Swing misc tests

Changes: https://git.openjdk.org/jdk/pull/15582/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=15582&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8315600
  Stats: 209 lines in 3 files changed: 209 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/15582.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/15582/head:pull/15582

PR: https://git.openjdk.org/jdk/pull/15582