enable Alpn_H3_Success test

[wfurt]

I could not reproduce the failure nor I see obvious reason why this would fail.
This may be victim of the deadlock fixed in #56600.

It is curious that the file has tests with the same pattern .... and they are all disabled.
All but one - ServerCertificateCustomValidationCallback_Succeeds added by @ManickaP.
That one is also lacking await on serverTask so we would not know if that task hangs or fails (as long as it does enough work to make client happy)

To move forward, I updated the test with similar pattern and without the SemaphoreSlim.
If it ever fails again, hopeful we would get more visibility.

fixes #56609

[ghost]

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Issue Details

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I could not reproduce the failure nor I see obvious reason why this would fail.
This may be victim of the deadlock fixed in #56600.

It is curious that the file has tests with the same pattern .... and they are all disabled.
All but one - ServerCertificateCustomValidationCallback_Succeeds added by @ManickaP.
That one is also lacking await on serverTask so we would not know if that task hangs or fails (as long as it does enough work to make client happy)

To move forward, I updated the test with similar pattern and without the SemaphoreSlim.
If it ever fails again, hopeful we would get more visibility.

fixes #56609

Author:	wfurt
Assignees:	wfurt
Labels:	area-System.Net.Http, test enhancement
Milestone:	-