[jdk21u-dev] RFR: 8340785: Update description of PassFailJFrame and samples

[Goetz Lindenmaier]

I backport this for parity with 21.0.6-oracle.

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Commit messages:
 - Backport 5063494f5b0859a396b4e41096793c777d4650b8

Changes: https://git.openjdk.org/jdk21u-dev/pull/1115/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk21u-dev&pr=1115&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8340785
  Stats: 159 lines in 1 file changed: 126 ins; 0 del; 33 mod
  Patch: https://git.openjdk.org/jdk21u-dev/pull/1115.diff
  Fetch: git fetch https://git.openjdk.org/jdk21u-dev.git pull/1115/head:pull/1115

PR: https://git.openjdk.org/jdk21u-dev/pull/1115