peer+funding: remove unneeded channel handoff code with the breach arbiter

We no longer need to hand off new channels that come online as the
chainWatcher will be persistent, and always have an active signal for
the entire lifetime of the channel.

discovery/gossiper.go

@@ -1019,7 +1019,7 @@ func (d *AuthenticatedGossiper) retransmitStaleChannels() error {
 		// existence.
 		if info.AuthProof == nil {
 			log.Debugf("Skipping retransmission of channel "+
-				"without AuthProof: %v", info)
+				"without AuthProof: %v", info.ChannelID)
 			return nil
 		}