[jdk21u-dev] RFR: 8345547: test/jdk/javax/swing/text/DefaultEditorKit/4278839/bug4278839.java fails in ubuntu22.04

[Goetz Lindenmaier]

I backport this test change as it also goes to 21.0.9-oracle

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Commit messages:
 - Backport e46d822aebee02d3cb4862c204293d388f6f3466

Changes: https://git.openjdk.org/jdk21u-dev/pull/1785/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk21u-dev&pr=1785&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8345547
  Stats: 37 lines in 1 file changed: 9 ins; 14 del; 14 mod
  Patch: https://git.openjdk.org/jdk21u-dev/pull/1785.diff
  Fetch: git fetch https://git.openjdk.org/jdk21u-dev.git pull/1785/head:pull/1785

PR: https://git.openjdk.org/jdk21u-dev/pull/1785