RFR: 8345468: test/jdk/javax/swing/JScrollBar/4865918/bug4865918.java fails in ubuntu22.04

[Prasanta Sadhukhan]

Test is failing in OCI system citing

java.lang.Error: The scrollbar block increment is incorect
at bug4865918.main(bug4865918.java:68) 

seemingly because focus is not in scrollbar..Added stability delay to make test execution wait after frame visibility and made frame to center of screen.
Test passed in several OCI systems with this modification...

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Commit messages:
 - 8345468: test/jdk/javax/swing/JScrollBar/4865918/bug4865918.java fails in ubuntu22.04

Changes: https://git.openjdk.org/jdk/pull/22540/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=22540&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8345468
  Stats: 28 lines in 1 file changed: 7 ins; 12 del; 9 mod
  Patch: https://git.openjdk.org/jdk/pull/22540.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/22540/head:pull/22540

PR: https://git.openjdk.org/jdk/pull/22540