[jdk25u-dev] RFR: 8339791: Refactor MiscUndecorated/ActiveAWTWindowTest.java

[Roland Mesde]

Backporting JDK-8339791: Refactor MiscUndecorated/ActiveAWTWindowTest.java.

This PR refactors ActiveAWTWindowTest.java to use CountDownLatch instead of object monitors/wait/notify, replaces ExtendedRobot with Robot, ensures EDT compliance, and removes boilerplate code for simpler, clearer synchronization.

For parity with Oracle JDK.

Ran related tests on linux-x64, linux-aarch64, macos-aarch64 and windows-x64:

make test TEST=test/jdk/java/awt/Frame/MiscUndecorated/ActiveAWTWindowTest.java

Results attached:

[macos-aarch64-specific-test.log](https://github.com/user-attachments/files/25215049/macos-aarch64-specific-test.log)
[windows-x64-specific-test.log](https://github.com/user-attachments/files/25215313/windows-x64-specific-test.log)
[linux-x64-specific-test.log](https://github.com/user-attachments/files/25215525/linux-x64-specific-test.log)
[linux-aarch64-specific-test.log](https://github.com/user-attachments/files/25215526/linux-aarch64-specific-test.log)

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Commit messages:
 - Backport a306f88a8456be454f4954c7e4fb8a1273344b5b

Changes: https://git.openjdk.org/jdk25u-dev/pull/248/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk25u-dev&pr=248&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8339791
  Stats: 160 lines in 1 file changed: 26 ins; 89 del; 45 mod
  Patch: https://git.openjdk.org/jdk25u-dev/pull/248.diff
  Fetch: git fetch https://git.openjdk.org/jdk25u-dev.git pull/248/head:pull/248

PR: https://git.openjdk.org/jdk25u-dev/pull/248