RFR: 8327401: Some jtreg tests fail on Wayland without any tracking bug

[Alexander Zvegintsev]

These changes are intended to stabilize testing on Wayland in X11 compatibility mode.

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Many tests may fail if there is no `robot.delay()` call after `robot.waitForIdle()` (right after displaying a window).
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Some tests do not release previously pressed mouse button/key, this leads to other test failures later, but it is not a problem for X11 session.
I haven't checked this, but it looks like the XWayland server does not release the key/button emulated by XTEST when the client application disconnects, while the regular X11 server does.

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For some tests it is critical to call AWT code on EDT(it prevents NPE):
java/awt/List/KeyEventsTest/KeyEventsTest.java
java/awt/Paint/ListRepaint.java

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Some other explanations can be found inline in the comments for a specific test.
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Testing is green on all platforms.

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Commit messages:
 - 8327401: Some jtreg tests fail on Wayland without any tracking bug

Changes: https://git.openjdk.org/jdk/pull/19339/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=19339&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8327401
  Stats: 736 lines in 24 files changed: 300 ins; 213 del; 223 mod
  Patch: https://git.openjdk.org/jdk/pull/19339.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/19339/head:pull/19339

PR: https://git.openjdk.org/jdk/pull/19339