Make IIS functional test run on helix(#9484)

src/Servers/IIS/IIS/test/IIS.Tests/ClientDisconnectTests.cs

@@ -178,7 +178,7 @@ namespace Microsoft.AspNetCore.Server.IISIntegration.FunctionalTests
         }
 
         [ConditionalFact]
-        [Flaky("https://github.com/aspnet/AspNetCore-Internal/issues/1831", FlakyOn.All)]
+        [Repeat(100)]
         public async Task ReaderThrowsCancelledException()
         {
             var requestStartedCompletionSource = CreateTaskCompletionSource();

src/Servers/IIS/IIS/test/IIS.Tests/IIS.Tests.csproj

@@ -5,8 +5,11 @@
   <PropertyGroup>
     <TargetFramework>netcoreapp3.0</TargetFramework>
     <InProcessTestSite>true</InProcessTestSite>
+    <IsIISTest>true</IsIISTest>
   </PropertyGroup>
 
+  <Import Project="../FunctionalTest.props" />
+
   <ItemGroup>
     <ProjectReference Include="..\Common.Tests\Common.Tests.csproj" />
     <ProjectReference Include="$(RepositoryRoot)src\Hosting\Server.IntegrationTesting\src\Microsoft.AspNetCore.Server.IntegrationTesting.csproj" />