RFR: 8367898: Skip StageFocusTest on Linux

[Andy Goryachev]

On Wed, 17 Sep 2025 15:00:01 GMT, Kevin Rushforth <kcr at openjdk.org> wrote:

> Skip `StageFocusTest` on Linux until [JDK-8367893](https://bugs.openjdk.org/browse/JDK-8367893) is fixed.
> 
> Also tested on macOS and Windows to verify that the test is still run.

ship it!

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Marked as reviewed by angorya (Reviewer).

PR Review: https://git.openjdk.org/jfx/pull/1909#pullrequestreview-3236358332