Dispose CTS in HubConnection streaming (#51137)

Co-authored-by: Brennan <[email protected]>

Author: github-actions[bot]

src/SignalR/clients/csharp/Client.Core/src/HubConnection.cs

@@ -853,7 +853,7 @@ async Task ReadChannelStream()
             }
         }
 
-        return CommonStreaming(connectionState, streamId, ReadChannelStream);
+        return CommonStreaming(connectionState, streamId, ReadChannelStream, tokenSource);
     }
 
     // this is called via reflection using the `_sendIAsyncStreamItemsMethod` field
@@ -870,11 +870,14 @@ async Task ReadAsyncEnumerableStream()
             }
         }
 
-        return CommonStreaming(connectionState, streamId, ReadAsyncEnumerableStream);
+        return CommonStreaming(connectionState, streamId, ReadAsyncEnumerableStream, tokenSource);
     }
 
-    private async Task CommonStreaming(ConnectionState connectionState, string streamId, Func<Task> createAndConsumeStream)
+    private async Task CommonStreaming(ConnectionState connectionState, string streamId, Func<Task> createAndConsumeStream, CancellationTokenSource cts)
     {
+        // make sure we dispose the CTS created by StreamAsyncCore once streaming completes
+        using var _ = cts;
+
         Log.StartingStream(_logger, streamId);
         string? responseError = null;
         try