remove useless if-else-loop

[harmening]

https://github.com/ibs-lab/cedalion/blob/dev/src/cedalion/dot/head_model.py#L667-L670
this if else loop has the same output

[emiddell]

Thanks for catching this, @harmening!

The idea was to make scale_to_landmarks work irrespectively if the user passes a head model in voxel or scanner space:

rec = cedalion.data.get_fingertappingDOT()

head_ijk = cedalion.dot.get_standard_headmodel("colin27")
head_ras = head_ijk.apply_transform(head_ijk.t_ijk2ras)

head_scaled_1 = head_ijk.scale_to_landmarks(rec.geo3d)
head_scaled_2 = head_ras.scale_to_landmarks(rec.geo3d)

assert_allclose(head_scaled_1.brain.vertices.data, head_scaled_2.brain.vertices.data)

But the code did not do that :)