Meet interface expectation for active record.

Count must still accept a second parameter.
https://github.com/rails/rails/blob/0ef8a244231c355cab7f4d032efed51ef5ddfe99/activerecord/lib/active_record/relation/calculations.rb#L30

Causes issues with gems that expect this interface to be consistent.

I'm not entirely sure why this method is here. I assume its for a reason.

This change should be backported to other branches.