[QUIC] Observe exceptions from _connectionCloseTcs

[ManickaP]

Fixes #112094

Observing the exception the same way as channel does in:

runtime/src/libraries/System.Threading.Channels/src/System/Threading/Channels/ChannelUtilities.cs

Lines 38 to 45 in ff604c2

	if (tcs.TrySetException(error))
	{
	// Suppress unobserved exceptions from Completion tasks, as the exceptions will generally
	// have been surfaced elsewhere (which may end up making a consumer not consume the completion
	// task), and even if they weren't, they're created by a producer who will have "seen" them (in
	// contrast to them being created by some method call failing as part of user code).
	_ = tcs.Task.Exception;
	}

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[CarnaViire]

Should we extract it as a method? as it's used 3 times