RFR: 8280482: Window transparency bug on Linux

[Tejesh R]

The bug mentions about transparency issue on Linux which actually got resolved with [JDK-8006421](https://bugs.openjdk.org/browse/JDK-8006421) fix. Now there is another problem related to the bug, which is screen selection going wrong during checking for new screen when the test is run. The problem is that (As seen in the pictures attached in bug) the transparency is lost for windows which are in screen 0 (default screen) too, which is not supposed to happen where windows on screen 1 should have lost there transparency. The main reason being the call to `toGlobal()` when window bounds are passed to `checkIfOnNewScreen` method. I didn't get the actual reason for `toGlobal` being used here (actually not required to check monitor number), but it actually doubled the X position of the window [here]( https://github.com/openjdk/jdk/blob/4b1403d06b99b91ddd89ad6e54669b0595f1f8e5/src/java.desktop/unix/classes/sun/awt/X11/XBaseWindow.java#L776). Removing `toGlobal` solve the issue and neither 
 didn't cause any regression (existing test + the reason `toGlobal()` was added [JDK-8143295](https://bugs.openjdk.org/browse/JDK-8143295)).

The automated test fails if GC is changed for windows within screen 0 (default screen). CI testing is green.

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Commit messages:
 - Fix + Automated test

Changes: https://git.openjdk.org/jdk/pull/14825/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=14825&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8280482
  Stats: 151 lines in 2 files changed: 149 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/jdk/pull/14825.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/14825/head:pull/14825

PR: https://git.openjdk.org/jdk/pull/14825