Remove obsolete feature_maps? method

It isn't used since commit c34aa5412.

app/models/concerns/mappable.rb

@@ -4,9 +4,5 @@ module Mappable
   included do
     has_one :map_location, dependent: :destroy
     accepts_nested_attributes_for :map_location, allow_destroy: true, reject_if: :all_blank
-
-    def feature_maps?
-      Setting["feature.map"].present?
-    end
   end
 end