multi: add DeleteChannelEdges to VersionedGraph

Add version-aware DeleteChannelEdges method to VersionedGraph and
update call sites in graph builder, rpcserver, and server to use
versioned graphs. This ensures channel deletion operations are
properly scoped to the correct gossip version.

rpcserver.go

@@ -3196,7 +3196,7 @@ func createRPCCloseUpdate(
 // abandonChanFromGraph attempts to remove a channel from the channel graph. If
 // we can't find the chanID in the graph, then we assume it has already been
 // removed, and will return a nop.
-func abandonChanFromGraph(chanGraph *graphdb.ChannelGraph,
+func abandonChanFromGraph(chanGraph *graphdb.VersionedGraph,
 	chanPoint *wire.OutPoint) error {
 
 	// First, we'll obtain the channel ID. If we can't locate this, then
@@ -3237,7 +3237,8 @@ func (r *rpcServer) abandonChan(chanPoint *wire.OutPoint,
 	if err != nil {
 		return err
 	}
-	err = abandonChanFromGraph(r.server.graphDB, chanPoint)
+	// TODO: update to support deletions for v2 channels.
+	err = abandonChanFromGraph(r.server.v1Graph, chanPoint)
 	if err != nil {
 		return err
 	}