Add timeout checking logic back to LongRunningOrchestration

Added back the logic to check which task completed and throw TimeoutException
if the timer completes first, as requested by code review.

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

Author: Copilot

test/Grpc.IntegrationTests/GrpcDurableTaskClientIntegrationTests.cs

@@ -639,7 +639,12 @@ static async Task<string> LongRunningOrchestration(TaskOrchestrationContext cont
             // Wait for external event or a timer (30 seconds) to allow suspend/resume operations
             Task<string> eventTask = context.WaitForExternalEvent<string>("event");
             Task timerTask = context.CreateTimer(TimeSpan.FromSeconds(30), CancellationToken.None);
-            await Task.WhenAny(eventTask, timerTask);
+            Task completedTask = await Task.WhenAny(eventTask, timerTask);
+
+            if (completedTask == timerTask)
+            {
+                throw new TimeoutException("Timed out waiting for external event 'event'.");
+            }
 
             if (shouldThrow)
             {