refactor(rate_limit): inline single-use eval_incr_script helper

      # otherwise.

      def incr_with_ttl(redis_key, period, cost)

        @redis.with do |conn|

          raw_count, ttl = eval_incr_script(conn, redis_key, period, cost)

          raw_count, ttl = INCR_SCRIPT.eval(conn, keys: [redis_key], argv: [period, cost])

          [Float(raw_count), ttl]

        end

      end

        end

      end

      def eval_incr_script(conn, redis_key, period, cost)

        INCR_SCRIPT.eval(conn, keys: [redis_key], argv: [period, cost])

      end

      def log_error(error, identifier)

        @logger.warn(

          message: "rate_limit_error",