RFR: 8277240: java/awt/Graphics2D/ScaledTransform/ScaledTransform.java dialog does not get disposed

[Phil Race]

This test has had reports of failures over the years notably on Linux.
I think the large number of XVisuals may have something to do with it.
I've updated it quite a bit and limited the number of dialogs it creates - we really don't need to test 300 of them
This new version has passed hundreds of iterations.

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Commit messages:
 - 8277240

Changes: https://git.openjdk.org/jdk/pull/21942/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=21942&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8277240
  Stats: 80 lines in 1 file changed: 49 ins; 12 del; 19 mod
  Patch: https://git.openjdk.org/jdk/pull/21942.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/21942/head:pull/21942

PR: https://git.openjdk.org/jdk/pull/21942