Clean up and open source some of the AWT window tests. Automated test `OwnedWindowShowTest.java` is verified in our CI also and it passes on all platforms.
------------- Commit messages: - 8341162: Open source some of the AWT window test Changes: https://git.openjdk.org/jdk/pull/21284/files Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=21284&range=00 Issue: https://bugs.openjdk.org/browse/JDK-8341162 Stats: 341 lines in 4 files changed: 341 ins; 0 del; 0 mod Patch: https://git.openjdk.org/jdk/pull/21284.diff Fetch: git fetch https://git.openjdk.org/jdk.git pull/21284/head:pull/21284 PR: https://git.openjdk.org/jdk/pull/21284
