Initialize important services before unattended installs (#17366)

* Added new notification to hook in after the premigrations and use this to init different services.

* Force MaxDegreeOfParallelism to 1, while investigating scopes

* Tried some more workarounds

* Updated scopes and changed parallel to non parallel to ensure migration works

* Missing scope

* Make it parallel again - The secret is, the SuppressFlow needs to be when you create the task, but not on the await!.

* Fixed issue when DEBUG_SCOPES is not added to tests.

* Remove test exception

* Try build on ubuntu again, even that we know it can be stuck. Just a test to see if all tests pass

* Updated comment

---------

Co-authored-by: kjac <kja@umbraco.dk>

src/Umbraco.Core/DependencyInjection/UmbracoBuilder.cs

@@ -416,7 +416,8 @@ namespace Umbraco.Cms.Core.DependencyInjection
 
             // Routing
             Services.AddUnique<IDocumentUrlService, DocumentUrlService>();
-            Services.AddHostedService<DocumentUrlServiceInitializer>();
+            Services.AddNotificationAsyncHandler<UmbracoApplicationStartingNotification, DocumentUrlServiceInitializerNotificationHandler>();
+
         }
     }
 }