multi: remove kvdb.RTx from ForEachNodeChannel

Since we have not removed all call-sites that make use of this
parameter, we can remove it. This helps hide DB-specific details from
the interface we will introduce for the graph store.

rpcserver.go

@@ -56,7 +56,6 @@ import (
 	"github.com/lightningnetwork/lnd/input"
 	"github.com/lightningnetwork/lnd/invoices"
 	"github.com/lightningnetwork/lnd/keychain"
-	"github.com/lightningnetwork/lnd/kvdb"
 	"github.com/lightningnetwork/lnd/labels"
 	"github.com/lightningnetwork/lnd/lncfg"
 	"github.com/lightningnetwork/lnd/lnrpc"
@@ -6959,7 +6958,7 @@ func (r *rpcServer) GetNodeInfo(ctx context.Context,
 	)
 
 	err = graph.ForEachNodeChannel(node.PubKeyBytes,
-		func(_ kvdb.RTx, edge *models.ChannelEdgeInfo,
+		func(edge *models.ChannelEdgeInfo,
 			c1, c2 *models.ChannelEdgePolicy) error {
 
 			numChannels++
@@ -7641,7 +7640,7 @@ func (r *rpcServer) FeeReport(ctx context.Context,
 
 	var feeReports []*lnrpc.ChannelFeeReport
 	err = channelGraph.ForEachNodeChannel(selfNode.PubKeyBytes,
-		func(_ kvdb.RTx, chanInfo *models.ChannelEdgeInfo,
+		func(chanInfo *models.ChannelEdgeInfo,
 			edgePolicy, _ *models.ChannelEdgePolicy) error {
 
 			// Self node should always have policies for its