Mark failing tests with issue.

Author: Lakshmi Priya Sekar

src/System.Net.Http/tests/FunctionalTests/HttpClientHandlerTest.Authentication.cs

@@ -85,6 +85,7 @@ public static IEnumerable<object[]> Authentication_TestData()
             yield return new object[] { "Basic something, Digest something", false };
 
             // Add digest tests fail on CurlHandler.
+            // TODO: #27113: Fix failing authentication test cases on different httpclienthandlers.
             if (PlatformDetection.IsWindows)
             {
                 yield return new object[] { "Digest realm=\"testrealm\" nonce=\"testnonce\"", false };

src/System.Net.Http/tests/FunctionalTests/SocketsHttpHandlerTest.cs

@@ -155,6 +155,7 @@ public async void SocketsHttpHandler_Authentication_Succeeds(string authenticate
         public static IEnumerable<object[]> Authentication_SocketsHttpHandler_TestData()
         {
             // These test cases pass on SocketsHttpHandler, fail everywhere else.
+            // TODO: #27113: Fix failing authentication test cases on different httpclienthandlers.
             yield return new object[] { "Basic realm=\"testrealm1\" basic realm=\"testrealm1\"", true };
             yield return new object[] { "Basic something digest something", true };
             yield return new object[] { "Digest ", false };