RFR: 8159599: [TEST_BUG] java/awt/Modal/ModalInternalFrameTest/ModalInternalFrameTest.java

[Alexander Zvegintsev]

The SimpleWindowActivationTest test does not fail even without modifications(multiple CI test runs are green).
So just remove it from ProblemList would be enough.

However I did some clean up and added some delays for  "extra safety".

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Commit messages:
 - initial
 - initial

Changes: https://git.openjdk.java.net/jdk/pull/8244/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=8244&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8159599
  Stats: 23 lines in 2 files changed: 13 ins; 3 del; 7 mod
  Patch: https://git.openjdk.java.net/jdk/pull/8244.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/8244/head:pull/8244

PR: https://git.openjdk.java.net/jdk/pull/8244