UIManager.getInstance().getLookAndFeel().setDefaultFormTransitionIn(null);
UIManager.getInstance().getLookAndFeel().setDefaultFormTransitionOut(null);
and also
UIManager.getInstance().getLookAndFeel().setDefaultFormTransitionIn(CommonTransitions.createEmpty());
UIManager.getInstance().getLookAndFeel().setDefaultFormTransitionOut(CommonTransitions.createEmpty());
but it did not have any effect.
So for each form I had to execute:
form.setTransitionInAnimator(CommonTransitions.createEmpty());
form.setTransitionOutAnimator(CommonTransitions.createEmpty());
which worked fine.
It would be nice to setup one time in the code as you mentioned. But I guess I did not do that right with LookAndFeel class.