Fix test failing when run in a batch due to not having the NetworkManager singleton

Author: noellie-velez

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

@@ -808,6 +808,7 @@ protected void CreateServerAndClients(int numberOfClients)
             m_NumberOfClients = numberOfClients;
             m_ClientNetworkManagers = clients;
             m_ServerNetworkManager = server;
+            NetworkLog.NetworkManagerOverride = server;
 
             var managers = clients.ToList();
             if (!m_UseCmbService)