[#502] Fixed User.active_local_user_query to return users with nil or missing `info.deactivated`. Adjusted test.

Indices in postgresql rely on operators, so they won't be used if you use only functions.

any actual callee will be dealing with a User struct to begin with, so
just check the child struct inside User.superuser?/1 with pattern matching.

auth_active?/1 can check remote users and return true directly.

user: use pattern matching to determine if user is local or remote instead of the previous hairy logic

Will work for missing users and badly migrated users.

because of user refetch, accounts can stop existing (get_from_ap_id() can fail), accordingly
filter the follow requests for these failures.