Revert "[PERF] Speed up integer type casting from DB"

This reverts commit 6f7910ae and 52c70d49.

Query params are type cased through the same method, so this approach doesn't work.

activerecord/lib/active_record/type/integer.rb

@@ -12,10 +12,7 @@ def type
         :integer
       end
 
-      def type_cast_from_database(value)
-        return if value.nil?
-        value.to_i
-      end
+      alias type_cast_for_database type_cast
 
       protected