[Identity] Fix flaky test (#12771)

Author: javiercn

src/Identity/test/Identity.FunctionalTests/Bootstrap3Tests/UIFramewrokAttributeTest.cs

@@ -26,7 +26,7 @@ public void DefaultWebSite_DefaultsToBootstrap3()
             var hasV3Part = false;
             var hasV4Part = false;
             var factory = Factory.WithWebHostBuilder(
-                whb => whb.UseStartup<Startup>().ConfigureServices(
+                whb => whb.ConfigureServices(
                     services => services.AddMvc().ConfigureApplicationPartManager(
                         apm => (hasV3Part, hasV4Part) = (HasPart(apm, "V3"), HasPart(apm, "V4")))));
 

src/Identity/test/Identity.FunctionalTests/Infrastructure/ServerFactory.cs

@@ -37,13 +37,10 @@ public ServerFactory()
         }
 
         public string BootstrapFrameworkVersion { get; set; } = "V4";
-        private bool IsHelixCI => typeof(ServerFactory<,>).Assembly.GetCustomAttributes<AssemblyMetadataAttribute>()
-            .Any(a => a.Key == "Microsoft.AspNetCore.Testing.IsHelixCI");
 
         protected override IHostBuilder CreateHostBuilder()
         {
-            Program.UseStartup = false;
-            return base.CreateHostBuilder();
+            return Program.CreateHostBuilder(new[] { "--use-startup=false" });
         }
 
         protected override void ConfigureWebHost(IWebHostBuilder builder)

src/Identity/testassets/Identity.DefaultUI.WebSite/Program.cs

@@ -2,6 +2,7 @@
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
 using System.IO;
+using System.Linq;
 using System.Reflection;
 using Microsoft.AspNetCore.Hosting;
 using Microsoft.Extensions.Configuration;
@@ -17,13 +18,11 @@ public static void Main(string[] args)
             CreateHostBuilder(args).Build().Run();
         }
 
-        public static bool UseStartup { get; set; } = true;
-
         public static IHostBuilder CreateHostBuilder(string[] args) =>
             Host.CreateDefaultBuilder(args)
                 .ConfigureWebHostDefaults(webBuilder =>
                 {
-                    if (UseStartup)
+                    if (!args.Contains("--use-startup=false"))
                     {
                         webBuilder.UseStartup<Startup>();
                     }