[jdk21u-dev] RFR: 8315883: Open source several Swing JToolbar tests

[Goetz Lindenmaier]

I backport this for parity with 21.0.7-oracle

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Commit messages:
 - Backport 62c0a1b9ac6462233f3ee06af470be9844e9e226

Changes: https://git.openjdk.org/jdk21u-dev/pull/1273/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk21u-dev&pr=1273&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8315883
  Stats: 199 lines in 4 files changed: 199 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk21u-dev/pull/1273.diff
  Fetch: git fetch https://git.openjdk.org/jdk21u-dev.git pull/1273/head:pull/1273

PR: https://git.openjdk.org/jdk21u-dev/pull/1273