Fix flaky test by waiting for orchestration to start before checking status

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

Author: Copilot

test/Grpc.IntegrationTests/GrpcDurableTaskClientIntegrationTests.cs

@@ -420,8 +420,11 @@ public async Task ScheduleNewOrchestrationInstance_WithDedupeStatuses_AllowsCrea
                 OrchestrationRuntimeStatus.Failed));
 
         createdInstanceId.Should().Be(instanceId);
+
+        // Wait for the instance to start before checking status
+        await server.Client.WaitForInstanceStartAsync(instanceId, default);
 
-        // Verify the instance was created
+        // Verify the instance was created and is running
         OrchestrationMetadata? metadata = await server.Client.GetInstanceAsync(instanceId, false);
         metadata.Should().NotBeNull();
         metadata!.RuntimeStatus.Should().Be(OrchestrationRuntimeStatus.Running);