Update com.unity.netcode.gameobjects/Tests/Runtime/TestHelpers/NetcodeIntegrationTestHelpers.cs

Co-authored-by: Emma <emma.mcmillan@unity3d.com>

Author: NoelStephensUnity

com.unity.netcode.gameobjects/Tests/Runtime/TestHelpers/NetcodeIntegrationTestHelpers.cs

@@ -542,10 +542,7 @@ private static void SceneManagerValidationAndTestRunnerInitialization(NetworkMan
                 }
 
                 // The server already registers every scene loaded prior to startup, so only add the test runner scene if it is not already there.
-                if (!networkManager.SceneManager.ServerSceneHandleToClientSceneHandle.ContainsKey(scene.handle))
-                {
-                    networkManager.SceneManager.ServerSceneHandleToClientSceneHandle.Add(scene.handle, scene.handle);
-                }
+            networkManager.SceneManager.ServerSceneHandleToClientSceneHandle.TryAdd(scene.handle, scene.handle);
             }
         }