Close channels inside a Once and don't set channels to nil

[Zerpet]

rabbitmq-stream-go-client/pkg/raw/client.go

Lines 684 to 697 in 80ec3cc

	if tc.confirmsCh != nil {
	close(tc.confirmsCh)
	tc.confirmsCh = nil
	}
	if tc.chunkCh != nil {
	close(tc.chunkCh)
	tc.chunkCh = nil
	}
	if tc.socketClosedCh != nil {
	close(tc.socketClosedCh)
	tc.socketClosedCh = nil
	}

Setting the channel to nil comes at a risk of blocking infinitely if any receiver attempts to receive.

Receiving from a nil channel blocks forever.

https://go.dev/ref/spec#Receive_operator

It probably does not block inside the smart layer, but this is an unnecesary risk, when there's another option available to achieve idempotent shutdown()