RFR: 8169285: Re-enable javafx.swt tests

[Marius Hanl]

On Wed, 16 Apr 2025 18:48:09 GMT, Marius Hanl <mhanl at openjdk.org> wrote:

> With this change, you can now run the `swt` tests as easy as: `:swt:test -PSWT_TEST=true`.
> ![image](https://github.com/user-attachments/assets/928141b5-ac81-4b15-9d86-5ea87f47c1c4)
> 
> Note: At one point `IS_FULL_TEST` was used as well for the enablement of the tests. I don't see any reason for it, and one flag seems to be enough to me. But open for opinions on this one.

Checking the GHA build, `IS_FULL_TEST` actually might be needed. Linux fails with `org.eclipse.swt.SWTError: No more handles [gtk_init_check() failed]` when creating the `Display`.

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PR Comment: https://git.openjdk.org/jfx/pull/1783#issuecomment-2810485324