RFR: 8320349: Simplify FileChooserSymLinkTest.java by using single-window testUI [v2]

[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.

Alexey Ivanov has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase.

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Changes:
  - all: https://git.openjdk.org/jdk/pull/16718/files
  - new: https://git.openjdk.org/jdk/pull/16718/files/2f1e3150..2f1e3150

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=16718&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=16718&range=00-01

  Stats: 0 lines in 0 files changed: 0 ins; 0 del; 0 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