Fix unit tests

[markus-hinsche]

CI is failing, so this is the fix

Solution:

• data_dir is important for trainlib, so it needs to be defined
• RandGaussianSmoothd was sometimes (flapping, undeterministic test behavior) failing https://gist.github.com/markus-hinsche/8aa82283ea6e60bf1925d44573483ea5, so it was removed