Render border is stored either in the current View3D data (UI data, not
undoable), or in Scene's render data when in camera view (only undoable
case).
This commit removes the `UNDO` flag of the related operators, and
instead manually pushes an undo step when executed in camera view.
Pull Request: https://projects.blender.org/blender/blender/pulls/122767
c7bc6ba1f6