HTTP/3: Remove try/catch around IsSupported property

[JamesNK]

Steve added try/catch here #40376

IsSupported no longer throws: dotnet/runtime#67036

Try/catch can be removed.

[ghost]

Thanks for contacting us.

We're moving this issue to the .NET 7 Planning milestone for future evaluation / consideration. We would like to keep this around to collect more feedback, which can help us with prioritizing this work. We will re-evaluate this issue, during our next planning meeting(s).
If we later determine, that the issue has no community involvement, or it's very rare and low-impact issue, we will close it - so that the team can focus on more important and high impact issues.
To learn more about what to expect next and how this issue will be handled you can read more about our triage process here.

[JamesNK]

User reported this is broken again: #41123 (comment)

@SteveSandersonMS Could you double-check whether this is working or not?

[SteveSandersonMS]

@JamesNK Yes, it's working - see #41123 (comment)