RFR: 8339791: Refactor MiscUndecorated/ActiveAWTWindowTest.java

[Srinivas Mandalika]

The java/awt/Frame/MiscUndecorated/ActiveAWTWindowTest.java test uses object monitors and wait/notify to synchronise actions in the test.

Using CountDownLatch could make the test simpler, shorter, clearer.
Tested the code on a windows-x64, macos-x64 and lnux-x64 machines and the test is working as expected.

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Commit messages:
 - 8339791: Refactor MiscUndecorated/ActiveAWTWindowTest.java

Changes: https://git.openjdk.org/jdk/pull/26471/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=26471&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8339791
  Stats: 40 lines in 1 file changed: 4 ins; 22 del; 14 mod
  Patch: https://git.openjdk.org/jdk/pull/26471.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/26471/head:pull/26471

PR: https://git.openjdk.org/jdk/pull/26471