Prevent information loss on host shutdown

Do not pass global CancellationToken to persistence operations on host
shutdown. This way it is ensured that persistence operations are not
cancelled.

src/WorkflowCore/Services/BackgroundTasks/WorkflowConsumer.cs

@@ -55,7 +55,7 @@ protected override async Task ProcessItem(string itemId, CancellationToken cance
                     finally
                     {
                         WorkflowActivity.Enrich(result);
-                        await _persistenceStore.PersistWorkflow(workflow, result?.Subscriptions, cancellationToken);
+                        await _persistenceStore.PersistWorkflow(workflow, result?.Subscriptions);
                         await QueueProvider.QueueWork(itemId, QueueType.Index);
                         _greylist.Remove($"wf:{itemId}");
                     }