[jdk21u-dev] RFR: 8342524: Use latch in AbstractButton/bug6298940.java instead of delay

[Goetz Lindenmaier]

I backport this for parity with 21.0.8-oracle,

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Commit messages:
 - Backport 2bd8f026dbd449e810dc6ce96cd9235e5cb51a9b

Changes: https://git.openjdk.org/jdk21u-dev/pull/1521/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk21u-dev&pr=1521&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8342524
  Stats: 93 lines in 1 file changed: 93 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk21u-dev/pull/1521.diff
  Fetch: git fetch https://git.openjdk.org/jdk21u-dev.git pull/1521/head:pull/1521

PR: https://git.openjdk.org/jdk21u-dev/pull/1521