Remove Socket.ConnectAsync workaround

[pepone]

icerpc-csharp/src/IceRpc/Transports/Tcp/Internal/TcpConnection.cs

Lines 334 to 336 in 1701684

	// Workaround: a canceled Socket.ConnectAsync call can return successfully but the Socket is closed because
	// of the cancellation. See https://github.com/dotnet/runtime/issues/75889.
	cancellationToken.ThrowIfCancellationRequested();

Seems this was fixed in .NET 10 dotnet/runtime#116943

We can probably remove this workaround in main, we should test.