Not only is this simpler, but it also is more correct (for explanation
why, try holding both shift keys while dragging, and just releasing one
of them - the previous code would briefly turn aspect ratio off).
Closes https://github.com/ppy/osu/issues/22783.
If the difficulty being edited has unsaved changes, the editor exit flow
would prompt for save *after* the deletion method has run. This is
undesirable from a UX standpoint, and also leaves the user in a broken
state.
Thus, just fake an update of the last saved hash of the beatmap to fool
the editor into thinking that it's not dirty, so that the exit flow will
not show a save dialog.