RFR: 8320349: Simplify FileChooserSymLinkTest.java by using single-window testUI

[Alexey Ivanov]

Update `FileChooserSymLinkTest.java` to simplify its implementation by replacing `List<Window>` with `JFrame` of its `createTestUI` which now uses `PassFailJFrame.Builder testUI(PassFailJFrame.WindowCreator)` instead of `PassFailJFrame.Builder testUI(PassFailJFrame.WindowListCreator)`.

The test works correctly with and without the update.

This PR depends on #16717.

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Depends on: https://git.openjdk.org/jdk/pull/16717

Commit messages:
 - 8320349: Simplify FileChooserSymLinkTest.java by using single-window testUI

Changes: https://git.openjdk.org/jdk/pull/16718/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=16718&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8320349
  Stats: 4 lines in 1 file changed: 0 ins; 2 del; 2 mod
  Patch: https://git.openjdk.org/jdk/pull/16718.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/16718/head:pull/16718

PR: https://git.openjdk.org/jdk/pull/16718