connectionmanager: do not cancel all waiting channel if first is declined

For a declined channel, onReady wasn't called. Only onShutdown()
causing all waiting callbacks to be declined if the connecting
channel was declined.
Now onReady is always called if channel is declined or accepted,
so we call all callbacks correctly. This fix sporadic failures
in testMultipleChannelsOneDeclined where the git channel was
declined as the connecting channel.

Change-Id: I0ff7550c2f35cbcf20aaf796d56badfb18bec515