routing: fail stale HTLC attempts during startup

This commit adds a check during router's startup and fails the inflight
HTLCs if they are routing using channels unknown to us. The channels are
unknown because they are already closed, usually long time ago.

server.go

@@ -993,18 +993,19 @@ func newServer(cfg *Config, listenAddrs []net.Addr,
 	}
 
 	s.chanRouter, err = routing.New(routing.Config{
-		SelfNode:           selfNode.PubKeyBytes,
-		RoutingGraph:       graphsession.NewRoutingGraph(chanGraph),
-		Chain:              cc.ChainIO,
-		Payer:              s.htlcSwitch,
-		Control:            s.controlTower,
-		MissionControl:     s.missionControl,
-		SessionSource:      paymentSessionSource,
-		GetLink:            s.htlcSwitch.GetLinkByShortID,
-		NextPaymentID:      sequencer.NextID,
-		PathFindingConfig:  pathFindingConfig,
-		Clock:              clock.NewDefaultClock(),
-		ApplyChannelUpdate: s.graphBuilder.ApplyChannelUpdate,
+		SelfNode:            selfNode.PubKeyBytes,
+		RoutingGraph:        graphsession.NewRoutingGraph(chanGraph),
+		Chain:               cc.ChainIO,
+		Payer:               s.htlcSwitch,
+		Control:             s.controlTower,
+		MissionControl:      s.missionControl,
+		SessionSource:       paymentSessionSource,
+		GetLink:             s.htlcSwitch.GetLinkByShortID,
+		NextPaymentID:       sequencer.NextID,
+		PathFindingConfig:   pathFindingConfig,
+		Clock:               clock.NewDefaultClock(),
+		ApplyChannelUpdate:  s.graphBuilder.ApplyChannelUpdate,
+		FetchClosedChannels: s.chanStateDB.FetchClosedChannels,
 	})
 	if err != nil {
 		return nil, fmt.Errorf("can't create router: %w", err)