* Restrict scope of negotiation time out error logs
1. Log "negotiation failed" only if signal channel was active
within half window of negotiation timeout. Negotiation timeout currently
is at 15 seconds. Signal pings are every 10 seconds.
2. In transport.go, do not report negotiation timed out and do not
callback negotiation failure if the peer connection state is not
connected. Goal of negotiation failure tracker is to take remedial
action when an in-session negotiation fails. Seeing a bunch of cases
of the case hitting even without ICE connection forming. Negotiation
timer is not intended for those cases.
* fix test