Always use --apply-cop-headers in ThreadingAppTest (dotnet#58642)

Author: halter73

src/Components/test/E2ETest/Infrastructure/ServerFixtures/BlazorWasmTestAppFixture.cs

@@ -25,6 +25,8 @@ public class BlazorWasmTestAppFixture<TProgram> : WebHostServerFixture
     public string PathBase { get; set; }
     public string ContentRoot { get; private set; }
 
+    public bool RequiresMultithreadingHeaders { get; set; }
+
     protected override IHost CreateWebHost()
     {
         if (TestTrimmedOrMultithreadingApps)
@@ -61,7 +63,7 @@ protected override IHost CreateWebHost()
             args.Add(Environment);
         }
 
-        if (WebAssemblyTestHelper.MultithreadingIsEnabled())
+        if (RequiresMultithreadingHeaders || WebAssemblyTestHelper.MultithreadingIsEnabled())
         {
             args.Add("--apply-cop-headers");
         }

src/Components/test/E2ETest/Tests/ThreadingAppTest.cs

@@ -19,6 +19,7 @@ public ThreadingAppTest(
         ITestOutputHelper output)
         : base(browserFixture, serverFixture, output)
     {
+        serverFixture.RequiresMultithreadingHeaders = true;
     }
 
     protected override void InitializeAsyncCore()
@@ -28,12 +29,14 @@ protected override void InitializeAsyncCore()
     }
 
     [Fact]
+    [QuarantinedTest("https://github.com/dotnet/aspnetcore/issues/54761")]
     public void HasTitle()
     {
         Assert.Equal("Blazor standalone", Browser.Title);
     }
 
     [Fact]
+    [QuarantinedTest("https://github.com/dotnet/aspnetcore/issues/54761")]
     public void HasHeading()
     {
         Assert.Equal("Hello, world!", Browser.Exists(By.TagName("h1")).Text);
@@ -85,6 +88,7 @@ public void CounterPageCanUseThreads()
     }
 
     [Fact]
+    [QuarantinedTest("https://github.com/dotnet/aspnetcore/issues/54761")]
     public void HasFetchDataPage()
     {
         // Navigate to "Fetch data"
@@ -106,6 +110,7 @@ public void HasFetchDataPage()
     }
 
     [Fact]
+    [QuarantinedTest("https://github.com/dotnet/aspnetcore/issues/54761")]
     public void IsStarted()
     {
         // Read from property