Fix Performance/Sum cop (#24788)

app/lib/activity_tracker.rb

@@ -43,7 +43,7 @@ class ActivityTracker
 
     case @type
     when :basic
-      redis.mget(*keys).map(&:to_i).sum
+      redis.mget(*keys).sum(&:to_i)
     when :unique
       redis.pfcount(*keys)
     end

app/models/trends/history.rb

@@ -11,7 +11,7 @@ class Trends::History
     end
 
     def uses
-      with_redis { |redis| redis.mget(*@days.map { |day| day.key_for(:uses) }).map(&:to_i).sum }
+      with_redis { |redis| redis.mget(*@days.map { |day| day.key_for(:uses) }).sum(&:to_i) }
     end
 
     def accounts