RFR: 8336332: Rework tests to avoid unrelated stderr output [v7]

[Andy Goryachev]

On Thu, 18 Sep 2025 15:25:53 GMT, Kevin Rushforth <kcr at openjdk.org> wrote:

>> Andy Goryachev has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   cleanup
>
> modules/javafx.base/src/test/java/test/javafx/util/OutputRedirect.java line 73:
> 
>> 71: 
>> 72:     /// Returns the captured output, if any, or `null`.
>> 73:     /// @return the captured output string, or `null`
> 
> The empty string might be a better choice if there is no output.

this method is not used anymore, will remove.

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PR Review Comment: https://git.openjdk.org/jfx/pull/1897#discussion_r2360157411