Drastically shorten `move_in` test
Drastically shorten `move_in` test

This code tested `create_user` and `move_in` for historical
reasons (`create_user` has been extracted from `move_in` at some
point) so both the specific call to `create_user` as well as many of
the assertions are unrelated to `move_in`.  They have been removed.

agdsn/pycroft,agdsn/pycroft,agdsn/pycroft,agdsn/pycroft,agdsn/pycroft