Update usages of ! is with is not (#2584)

* Update usages of ! is with is not

* Content.IntegrationTests commit

* Content.Server commit

* Content.Shared commit

Co-authored-by: Metal Gear Sloth <metalgearsloth@gmail.com>

Content.Shared/Arcade/BlockGameMessages.cs

@@ -123,7 +123,7 @@ namespace Content.Shared.Arcade
 
             public int CompareTo(object? obj)
             {
-                if (!(obj is HighScoreEntry entry)) return 0;
+                if (obj is not HighScoreEntry entry) return 0;
                 return Score.CompareTo(entry.Score);
             }
         }