Quarantine recent test failures

- see also #21080 for another recent failure

Author: dougbu

src/Servers/Kestrel/test/InMemory.FunctionalTests/Http2/Http2StreamTests.cs

@@ -914,6 +914,7 @@ await InitializeConnectionAsync(async context =>
         }
 
         [Fact]
+        [QuarantinedTest]
         public async Task ContentLength_Received_MultipleDataFramesUnderSize_Reset()
         {
             IOException thrownEx = null;

src/SignalR/clients/csharp/Client/test/UnitTests/TimerAwaitableTests.cs

@@ -5,13 +5,15 @@
 using System.Runtime.CompilerServices;
 using System.Threading.Tasks;
 using Microsoft.AspNetCore.Internal;
+using Microsoft.AspNetCore.Testing;
 using Xunit;
 
 namespace Microsoft.AspNetCore.SignalR.Client.Tests
 {
     public class TimerAwaitableTests
     {
         [Fact]
+        [QuarantinedTest]
         public void FinalizerRunsIfTimerAwaitableReferencesObject()
         {
             var tcs = new TaskCompletionSource<object>(TaskCreationOptions.RunContinuationsAsynchronously);

src/Tools/dotnet-user-secrets/test/InitCommandTest.cs

@@ -32,6 +32,7 @@ public InitCommandTests(UserSecretsTestFixture fixture, ITestOutputHelper output
         private CommandContext MakeCommandContext() => new CommandContext(null, new TestReporter(_output), _console);
 
         [Fact]
+        [QuarantinedTest]
         public void AddsSecretIdToProject()
         {
             var projectDir = _fixture.CreateProject(null);