Migrated temp file cleanup background task to a hosted service.

src/Umbraco.Web.Common/Extensions/UmbracoCoreServiceCollectionExtensions.cs

@@ -294,6 +294,7 @@ namespace Umbraco.Extensions
         {
             services.AddHostedService<HealthCheckNotifier>();
             services.AddHostedService<KeepAlive>();
+            services.AddHostedService<TempFileCleanup>();
             return services;
         }