multiport: log lane up and down at debug

A lane coming up or going down is per-lane, per-tunnel, and repeats on the
keepalive: a node with many tunnels would bury its actual events under it. The
gauges are the place to watch lanes in aggregate, so drop these two to debug for
when you are looking at one tunnel. Probe failures stay at error.

lanes.go

@@ -487,7 +487,7 @@ func (f *Interface) probeLanes(hostinfo *HostInfo, now time.Time, nb, out []byte
 			p.retryAt = now.Add(laneRetryDelay(p.fails))
 			if up {
 				ls.txAddr[s].Store(nil)
-				hostinfo.logger(f.l).Info("Multiport lane demoted, probe unanswered", "lane", s)
+				hostinfo.logger(f.l).Debug("Multiport lane demoted, probe unanswered", "lane", s)
 			}
 			continue
 		}
@@ -598,6 +598,6 @@ func (f *Interface) handleLaneProbeAck(hostinfo *HostInfo, payload []byte) {
 	}
 
 	if ls.noteAck(int(payload[0]), payload[1], time.Now()) {
-		hostinfo.logger(f.l).Info("Multiport lane up", "lane", payload[0])
+		hostinfo.logger(f.l).Debug("Multiport lane up", "lane", payload[0])
 	}
 }