[jdk21u-dev] RFR: 8341982: Simplify JButton/bug4323121.java

[Goetz Lindenmaier]

I backport this for parity with 21.0.7-oracle.

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Commit messages:
 - Backport 6fa5cea984c31fbb74b39e1eec68daffea22ca92

Changes: https://git.openjdk.org/jdk21u-dev/pull/1336/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk21u-dev&pr=1336&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8341982
  Stats: 85 lines in 1 file changed: 24 ins; 40 del; 21 mod
  Patch: https://git.openjdk.org/jdk21u-dev/pull/1336.diff
  Fetch: git fetch https://git.openjdk.org/jdk21u-dev.git pull/1336/head:pull/1336

PR: https://git.openjdk.org/jdk21u-dev/pull/1336