[jdk17u-dev] RFR: 8306575: Clean up and open source four Dialog related tests

[Goetz Lindenmaier]

I backport this for parity with 17.0.9-oracle.

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Commit messages:
 - Backport 8d696aea9e1cefca97a760c017a5fde545facaa9

Changes: https://git.openjdk.org/jdk17u-dev/pull/1513/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk17u-dev&pr=1513&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8306575
  Stats: 587 lines in 4 files changed: 587 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk17u-dev/pull/1513.diff
  Fetch: git fetch https://git.openjdk.org/jdk17u-dev.git pull/1513/head:pull/1513

PR: https://git.openjdk.org/jdk17u-dev/pull/1513