This removes `seat <seat> keyboard_grouping keymap` and replaces it with
`seat <seat> keyboard_grouping smart`. The smart keyboard grouping will
group based on both the keymap and repeat info. The reasoning for this
is that deciding what the repeat info should be for a group is either
arbitrary or non-deterministic when multiple keyboards in the group have
repeat info configured (unless somehow exposed to the user in a
reproducible uniquely identifiable fashion).