[HTTP/3] SendStreamLimitRequestsConcurrently_Succeeds times out

[mdh1418]

System.Net.Http.Functional.Tests.SocketsHttpHandlerTest_Http3_MsQuic.SendStreamLimitRequestsConcurrently_Succeeds(streamLimit: 10) [FAIL]
      System.TimeoutException : The operation has timed out.
      Stack Trace:
        /_/src/libraries/Common/tests/System/Threading/Tasks/TaskTimeoutExtensions.cs(49,0): at System.Threading.Tasks.TaskTimeoutExtensions.WhenAllOrAnyFailed(Task[] tasks, Int32 millisecondsTimeout)
        /_/src/libraries/System.Net.Http/tests/FunctionalTests/HttpClientHandlerTest.Http3.cs(163,0): at System.Net.Http.Functional.Tests.HttpClientHandlerTest_Http3.SendStreamLimitRequestsConcurrently_Succeeds(Int32 streamLimit)
        --- End of stack trace from previous location ---

log: https://helixre8s23ayyeko0k025g8.blob.core.windows.net/dotnet-runtime-refs-pull-54845-merge-b3a250ac333f4a61ad/System.Net.Http.Functional.Tests/console.fb7bf6d4.log?sv=2019-07-07&se=2021-08-09T14%3A21%3A02Z&sr=c&sp=rl&sig=CXj3eKgQpJ%2B6oxAsRdMe0xpZUHxHXuGHya1lGnOEa7s%3D
build: https://dev.azure.com/dnceng/public/_build/results?buildId=1246649&view=logs&j=d883cc86-ff08-5389-6fca-0d01451458f6&t=5fca1690-df52-529b-9100-c473a9350efd&l=151

Failures 5/20-7/20 (incl. PRs):

Day	Failures
7/19	2x Official run (1x Mock) + 8x PR
7/20	2x Official run + 17x PR (2x Mock)

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Issue Details

---

System.Net.Http.Functional.Tests.SocketsHttpHandlerTest_Http3_MsQuic.SendStreamLimitRequestsConcurrently_Succeeds(streamLimit: 10) [FAIL]
      System.TimeoutException : The operation has timed out.
      Stack Trace:
        /_/src/libraries/Common/tests/System/Threading/Tasks/TaskTimeoutExtensions.cs(49,0): at System.Threading.Tasks.TaskTimeoutExtensions.WhenAllOrAnyFailed(Task[] tasks, Int32 millisecondsTimeout)
        /_/src/libraries/System.Net.Http/tests/FunctionalTests/HttpClientHandlerTest.Http3.cs(163,0): at System.Net.Http.Functional.Tests.HttpClientHandlerTest_Http3.SendStreamLimitRequestsConcurrently_Succeeds(Int32 streamLimit)
        --- End of stack trace from previous location ---

log: https://helixre8s23ayyeko0k025g8.blob.core.windows.net/dotnet-runtime-refs-pull-54845-merge-b3a250ac333f4a61ad/System.Net.Http.Functional.Tests/console.fb7bf6d4.log?sv=2019-07-07&se=2021-08-09T14%3A21%3A02Z&sr=c&sp=rl&sig=CXj3eKgQpJ%2B6oxAsRdMe0xpZUHxHXuGHya1lGnOEa7s%3D
build: https://dev.azure.com/dnceng/public/_build/results?buildId=1246649&view=logs&j=d883cc86-ff08-5389-6fca-0d01451458f6&t=5fca1690-df52-529b-9100-c473a9350efd&l=151

Author:	mdh1418
Assignees:	-
Labels:	area-System.Net.Http
Milestone:	-

[karelz]

Test disabled in PR #56001 on 7/20