peer: don't reply if peer's request initial_graph_sync

We stopped requesting this from other nodes as it is very expensive as
the graph continues to grow. In this commit we will also stop
responding, as nodes are recommended to begin using the `gossip_queries`
and upcoming `extended_gossip_queries` to reconcile missing graph data.

peer.go

@@ -396,16 +396,6 @@ func (p *peer) initGossipSync() {
 		// bootstrapper to ensure we can find and connect to non-channel
 		// peers.
 		p.server.authGossiper.InitSyncState(p)
-
-	// If the remote peer has the initial sync feature bit set, then we'll
-	// being the synchronization protocol to exchange authenticated channel
-	// graph edges/vertexes, but only if they don't know of the new gossip
-	// queries.
-	case p.remoteLocalFeatures.HasFeature(lnwire.InitialRoutingSync):
-		srvrLog.Infof("Requesting full table sync with %x",
-			p.pubKeyBytes[:])
-
-		go p.server.authGossiper.SynchronizeNode(p)
 	}
 }