Quarantine recent test failures (#26295)

- see #26291 and #26294

src/Servers/IIS/IIS/test/Common.FunctionalTests/Inprocess/SynchronousReadAndWriteTests.cs

@@ -22,6 +22,7 @@ namespace Microsoft.AspNetCore.Server.IIS.FunctionalTests.InProcess
         }
 
         [ConditionalFact]
+        [QuarantinedTest("https://github.com/dotnet/aspnetcore/issues/26294")]
         public async Task ReadAndWriteSynchronously()
         {
             var content = new StringContent(new string('a', 100000));

src/Servers/Kestrel/test/InMemory.FunctionalTests/Http2/Http2ConnectionTests.cs

@@ -1503,6 +1503,7 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Core.Tests
         }
 
         [Fact]
+        [QuarantinedTest("https://github.com/dotnet/aspnetcore/issues/26291")]
         public Task Frame_MultipleStreams_RequestsNotFinished_DefaultMaxStreamsPerConnection_EnhanceYourCalmAfterDoubleMaxStreams()
         {
             // Kestrel tracks max streams per connection * 2