DualModeConnectAsync_DnsEndPointToHost_Helper fails in CI with TrueException on OSX

[ahsonkhan]

From dotnet/corefx#28992
OSX.1012.Amd64.Open-x64-Debug
System.Net.Sockets.Tests.DualModeConnectAsync/DualModeConnectAsync_DnsEndPointToHost_Helper(listenOn: ::, dualModeServer: True)
https://mc.dot.net/#/user/ahsonkhan/pr~2Fjenkins~2Fdotnet~2Fcorefx~2Fmaster~2F/test~2Ffunctional~2Fcli~2F/95b8f31c8f84213f3192a6b9d96e8b2ecdb2dcfe/workItem/System.Net.Sockets.Tests/analysis/xunit/System.Net.Sockets.Tests.DualModeConnectAsync~2FDualModeConnectAsync_DnsEndPointToHost_Helper(listenOn:%20::,%20dualModeServer:%20True)

Unhandled Exception of Type Xunit.Sdk.TrueException
Message :
Timed out while waiting for connection
Expected: True
Actual:   False
Stack Trace :
   at System.Net.Sockets.Tests.DualModeConnectAsync.DualModeConnectAsync_DnsEndPointToHost_Helper(IPAddress listenOn, Boolean dualModeServer) in /Users/dotnet-bot/j/workspace/dotnet_corefx/master/osx-TGroup_netcoreapp+CGroup_Debug+AGroup_x64+TestOuter_false_prtest/src/System.Net.Sockets/tests/FunctionalTests/DualModeSocketTest.cs:line 588

[karelz]

Duplicate of #22225