Disable SignalR in Elsa Server

Updated `useSignalR` flag to false in `Program.cs` due to Elsa Studio's current inability to send authenticated requests to the SignalR hub. This change ensures better security and stability until the necessary update is implemented.

src/bundles/Elsa.Server.Web/Program.cs

@@ -48,7 +48,7 @@
 const bool useMemoryStores = false;
 const bool useCaching = true;
 const bool useReadOnlyMode = false;
-const bool useSignalR = true;
+const bool useSignalR = false; // Disable until Elsa Studio is updated to send authenticated requests to the SignalR hub. 
 const bool useAzureServiceBus = false;
 const DistributedCachingTransport distributedCachingTransport = DistributedCachingTransport.MassTransit;
 const MassTransitBroker useMassTransitBroker = MassTransitBroker.Memory;