For undo/redo of position undo steps, currently we do some processing
that scales with the size of the mesh. The code is also more complex
than necessary-- we don't make use of the relations between some
concepts to simplify things.
This commit unifies the loops, mostly by making use of the fact that we
only need to modify the original mesh positions. When there are deform
modifiers a reevaluation will update the evaluated positions, and other-
wise, the original and evaluated positions are the same anyway.
Related to #129496.
Pull Request: https://projects.blender.org/blender/blender/pulls/129783
005e02d008