RFR: 8169285: Re-enable javafx.swt tests

[Marius Hanl]

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.

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Commit messages:
 - 8169285: Re-enable javafx.swt tests

Changes: https://git.openjdk.org/jfx/pull/1783/files
  Webrev: https://webrevs.openjdk.org/?repo=jfx&pr=1783&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8169285
  Stats: 3 lines in 1 file changed: 0 ins; 2 del; 1 mod
  Patch: https://git.openjdk.org/jfx/pull/1783.diff
  Fetch: git fetch https://git.openjdk.org/jfx.git pull/1783/head:pull/1783

PR: https://git.openjdk.org/jfx/pull/1783