Disable tests blocking CI (#55446)

* Turn off test FlushAsync_ThrowsIfWriterReaderWithException
* Turn off System.Net.NameResolution.Tests.GetHost* tests for SLES

Author: hoyosjs

src/libraries/System.IO.Pipelines/tests/FlushAsyncTests.cs

@@ -22,7 +22,7 @@ public void FlushAsync_ReturnsCompletedTaskWhenMaxSizeIfZero()
         }
 
         [Fact]
-        [ActiveIssue("https://github.com/dotnet/runtime/issues/50957", typeof(PlatformDetection), nameof(PlatformDetection.IsBrowser), nameof(PlatformDetection.IsMonoAOT))]
+        [ActiveIssue("https://github.com/dotnet/runtime/issues/55435")]
         public async Task FlushAsync_ThrowsIfWriterReaderWithException()
         {
             void ThrowTestException()

src/libraries/System.Net.NameResolution/tests/FunctionalTests/GetHostByNameTest.cs

@@ -4,6 +4,8 @@
 #pragma warning disable 0618 // use of obsolete methods
 
 using System.Net.Sockets;
+
+using Microsoft.DotNet.XUnitExtensions;
 using Xunit;
 
 namespace System.Net.NameResolution.Tests
@@ -106,17 +108,28 @@ public void DnsObsoleteGetHostByName_IPv6String_ReturnsOnlyGivenIP()
         [ActiveIssue("https://github.com/dotnet/runtime/issues/51377", TestPlatforms.iOS | TestPlatforms.tvOS | TestPlatforms.MacCatalyst)]
         public void DnsObsoleteGetHostByName_EmptyString_ReturnsHostName()
         {
+            if (PlatformDetection.IsSLES)
+            {
+                // See https://github.com/dotnet/runtime/issues/55271
+                throw new SkipTestException("SLES Tests environment is not configured for this test to work.");
+            }
             IPHostEntry entry = Dns.GetHostByName("");
 
             // DNS labels should be compared as case insensitive for ASCII characters. See RFC 4343.
             Assert.Contains(Dns.GetHostName(), entry.HostName, StringComparison.OrdinalIgnoreCase);
         }
 
-        [ActiveIssue("https://github.com/dotnet/runtime/issues/1488", TestPlatforms.OSX)]
         [ConditionalFact(typeof(PlatformDetection), nameof(PlatformDetection.IsNotArm64Process), nameof(PlatformDetection.IsThreadingSupported))] // [ActiveIssue("https://github.com/dotnet/runtime/issues/27622")]
+        [ActiveIssue("https://github.com/dotnet/runtime/issues/1488", TestPlatforms.OSX)]
         [ActiveIssue("https://github.com/dotnet/runtime/issues/51377", TestPlatforms.iOS | TestPlatforms.tvOS | TestPlatforms.MacCatalyst)]
         public void DnsObsoleteBeginEndGetHostByName_EmptyString_ReturnsHostName()
         {
+            if (PlatformDetection.IsSLES)
+            {
+                // See https://github.com/dotnet/runtime/issues/55271
+                throw new SkipTestException("SLES Tests environment is not configured for this test to work.");
+            }
+
             IPHostEntry entry = Dns.EndGetHostByName(Dns.BeginGetHostByName("", null, null));
 
             // DNS labels should be compared as case insensitive for ASCII characters. See RFC 4343.

src/libraries/System.Net.NameResolution/tests/FunctionalTests/GetHostEntryTest.cs

@@ -7,6 +7,7 @@
 using System.Threading;
 using System.Threading.Tasks;
 
+using Microsoft.DotNet.XUnitExtensions;
 using Xunit;
 
 namespace System.Net.NameResolution.Tests
@@ -21,13 +22,18 @@ public async Task Dns_GetHostEntryAsync_IPAddress_Ok()
         }
 
         [ActiveIssue("https://github.com/dotnet/runtime/issues/1488", TestPlatforms.OSX)]
-        
+        [ActiveIssue("https://github.com/dotnet/runtime/issues/51377", TestPlatforms.iOS | TestPlatforms.tvOS | TestPlatforms.MacCatalyst)]
         [ConditionalTheory(typeof(PlatformDetection), nameof(PlatformDetection.IsNotArm64Process))] // [ActiveIssue("https://github.com/dotnet/runtime/issues/27622")]
         [InlineData("")]
         [InlineData(TestSettings.LocalHost)]
-        [ActiveIssue("https://github.com/dotnet/runtime/issues/51377", TestPlatforms.iOS | TestPlatforms.tvOS | TestPlatforms.MacCatalyst)]
         public async Task Dns_GetHostEntry_HostString_Ok(string hostName)
         {
+            if (PlatformDetection.IsSLES)
+            {
+                // See https://github.com/dotnet/runtime/issues/55271
+                throw new SkipTestException("SLES Tests environment is not configured for this test to work.");
+            }
+
             try
             {
                 await TestGetHostEntryAsync(() => Task.FromResult(Dns.GetHostEntry(hostName)));
@@ -72,12 +78,20 @@ public async Task Dns_GetHostEntry_HostString_Ok(string hostName)
         }
 
         [ActiveIssue("https://github.com/dotnet/runtime/issues/1488", TestPlatforms.OSX)]
+        [ActiveIssue("https://github.com/dotnet/runtime/issues/51377", TestPlatforms.iOS | TestPlatforms.tvOS | TestPlatforms.MacCatalyst)]
         [ConditionalTheory(typeof(PlatformDetection), nameof(PlatformDetection.IsNotArm64Process))] // [ActiveIssue("https://github.com/dotnet/runtime/issues/27622")]
         [InlineData("")]
         [InlineData(TestSettings.LocalHost)]
-        [ActiveIssue("https://github.com/dotnet/runtime/issues/51377", TestPlatforms.iOS | TestPlatforms.tvOS | TestPlatforms.MacCatalyst)]
-        public async Task Dns_GetHostEntryAsync_HostString_Ok(string hostName) =>
+        public async Task Dns_GetHostEntryAsync_HostString_Ok(string hostName)
+        {
+            if (PlatformDetection.IsSLES)
+            {
+                // See https://github.com/dotnet/runtime/issues/55271
+                throw new SkipTestException("SLES Tests environment is not configured for this test to work.");
+            }
+
             await TestGetHostEntryAsync(() => Dns.GetHostEntryAsync(hostName));
+        }
 
         [Fact]
         public async Task Dns_GetHostEntryAsync_IPString_Ok() =>