Fix flaky AbortedStream test in Kestrel (#8010)

Author: jkotalik

src/Servers/Kestrel/test/InMemory.FunctionalTests/Http2/Http2TestBase.cs

@@ -25,6 +25,7 @@
 using Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Infrastructure;
 using Microsoft.AspNetCore.Server.Kestrel.Transport.Abstractions.Internal;
 using Microsoft.AspNetCore.Testing;
+using Microsoft.Extensions.Logging;
 using Microsoft.Net.Http.Headers;
 using Moq;
 using Xunit;
@@ -177,7 +178,11 @@ public Http2TestBase()
             _mockConnectionContext.Setup(c => c.Abort(It.IsAny<ConnectionAbortedException>())).Callback<ConnectionAbortedException>(ex =>
             {
                 // Emulate transport abort so the _connectionTask completes.
-                Task.Run(() => _pair.Application.Output.Complete(ex));
+                Task.Run(() =>
+                {
+                    TestApplicationErrorLogger.LogInformation(0, ex, "ConnectionContext.Abort() was called. Completing _pair.Application.Output.");
+                    _pair.Application.Output.Complete(ex);
+                });
             });
 
             _noopApplication = context => Task.CompletedTask;

src/Servers/Kestrel/test/InMemory.FunctionalTests/Http2/Http2TimeoutTests.cs

@@ -198,6 +198,9 @@ public async Task ResponseDrain_SlowerThanMinimumDataRate_AbortsConnection()
         [InlineData(Http2FrameType.CONTINUATION)]
         public async Task AbortedStream_ResetsAndDrainsRequest_RefusesFramesAfterCooldownExpires(Http2FrameType finalFrameType)
         {
+            // Remove callback that completes _pair.Application.Output on abort.
+            _mockConnectionContext.Reset();
+
             var mockSystemClock = _serviceContext.MockSystemClock;
 
             var headers = new[]