build-gnu.sh: Move {ch,run}con tests to Fedora VM and avoid wrong result

[oech3]

We can't build runcon and chcon without libselinux. But GNU no longer builds dummies of them. So move tests to Fedora VM: https://github.com/uutils/coreutils/actions/runs/20046833546/job/57494071620?pr=9607#step:15:34

Also some tests related with them were incorrectly passing due to false symlinks...

[github-actions]

GNU testsuite comparison:

Congrats! The gnu test tests/runcon/runcon-no-reorder is no longer failing!
Note: The gnu test tests/runcon/runcon-compute is now being skipped but was previously passing.

[github-actions]

GNU testsuite comparison:

Congrats! The gnu test tests/runcon/runcon-no-reorder is no longer failing!
Note: The gnu test tests/runcon/runcon-compute is now being skipped but was previously passing.

[github-actions]

GNU testsuite comparison:

GNU test failed: tests/runcon/runcon-compute. tests/runcon/runcon-compute is passing on 'main'. Maybe you have to rebase?
Congrats! The gnu test tests/runcon/runcon-no-reorder is no longer failing!

[oech3]

Note that runcon-compute passes when runcon is false. This is not a regression.
This should be commented.

[github-actions]

GNU testsuite comparison:

GNU test failed: tests/runcon/runcon-compute. tests/runcon/runcon-compute is passing on 'main'. Maybe you have to rebase?
Congrats! The gnu test tests/runcon/runcon-no-reorder is no longer failing!
Congrats! The gnu test tests/tail/inotify-dir-recreate is now passing!

[sylvestre]

@oech3 it caused a regression on GNU test failed: tests/runcon/runcon-compute. tests/runcon/runcon-compute is passing on 'main'. Maybe you have to rebase?
could you please have a look? thanks

[oech3]

runcon-compute was incorrectly passing by symlinking false binary to runcon.

[oech3]

So we should reset the result by someway. I don't know how to do that...