It turns out `BKE_mesh_copy_parameters` can be called while other
tools are running calculations, which meant that it was called at the
same time as `armature_deform_coords_impl`. Beause of that, we
shouldn't do any freeing (of the old vertex group names) there.
Since the materials are copied in the "for_eval" version anyway,
it seems to make sense to copy the vertex group name list there also.
Fixes T89877, and also the failing `deform_modifiers` test.
Differential Revision: https://developer.blender.org/D11936
0cc2a72f94