RFR: 8366852: java/awt/Choice/ChoiceMouseWheelTest/ChoiceMouseWheelTest.java test is failing

[Alexander Zvegintsev]

There are several major issues with the test:

1. The `frameExited` variable is set to true when the mouse pointer exits the frame. The test does not expect this to happen with the first mouse click on the `choice` when the mouse pointer is already over the test frame (frame mouseExited - > choice mouseEntered). A reset for the frameExited was added.
2. The test does not wait for the frame to appear after the call to `setVisible()`, so the test can start operating not on a fully visible window (e.g. one with an appearance animation). A delay has been added.
3. In macOS, the direction of rotation of the mouse wheel is different, which was not taken into account. 

Testing looks good.

-------------

Commit messages:
 - remove System.exit()
 - fix enter drop-down condition
 - cleanup
 - actual fix

Changes: https://git.openjdk.org/jdk/pull/27161/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=27161&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8366852
  Stats: 105 lines in 2 files changed: 37 ins; 22 del; 46 mod
  Patch: https://git.openjdk.org/jdk/pull/27161.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/27161/head:pull/27161

PR: https://git.openjdk.org/jdk/pull/27161