RFR: 8342401: [TESTBUG] javax/swing/JSpinner/8223788/JSpinnerButtonFocusTest.java test fails in ubuntu 22.04 on SBR Hosts

[Prasanta Sadhukhan]

Test probably was failing due to lack of delay between UI creation and test execution..Delay is added along with rendering frame at screen centre..Also added listener closer to UI creation within EDT
CI run for 100 iterations are ok on all platforms..

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

Commit messages:
 - 8342401: [TESTBUG] javax/swing/JSpinner/8223788/JSpinnerButtonFocusTest.java test fails in ubuntu 22.04 on SBR Hosts

Changes: https://git.openjdk.org/jdk/pull/27815/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=27815&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8342401
  Stats: 22 lines in 1 file changed: 10 ins; 9 del; 3 mod
  Patch: https://git.openjdk.org/jdk/pull/27815.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/27815/head:pull/27815

PR: https://git.openjdk.org/jdk/pull/27815