RFR: 8042381: Test javax/swing/JRootPane/4670486/bug4670486.java fails with Action has not been received

[Prasanta Sadhukhan]

This test was failing long time back probably due to samevm mode execution but not failing in recent run.
Reduce sutodelay time consistent with other test, move frame to center and added wait time after frame is made visible.

Several iterations of the test passed in all platforms (link in JBS)

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Commit messages:
 - Merge branch 'master' into JDK-8042381
 - 8042381: Test javax/swing/JRootPane/4670486/bug4670486.java fails with Action has not been received

Changes: https://git.openjdk.java.net/jdk/pull/8296/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=8296&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8042381
  Stats: 4 lines in 2 files changed: 2 ins; 1 del; 1 mod
  Patch: https://git.openjdk.java.net/jdk/pull/8296.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/8296/head:pull/8296

PR: https://git.openjdk.java.net/jdk/pull/8296