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.

graph/builder.go

@@ -13,7 +13,6 @@ import (
 	"github.com/lightningnetwork/lnd/chainntnfs"
 	graphdb "github.com/lightningnetwork/lnd/graph/db"
 	"github.com/lightningnetwork/lnd/graph/db/models"
-	"github.com/lightningnetwork/lnd/kvdb"
 	"github.com/lightningnetwork/lnd/lnutils"
 	"github.com/lightningnetwork/lnd/lnwallet"
 	"github.com/lightningnetwork/lnd/lnwire"
@@ -1276,8 +1275,7 @@ func (b *Builder) ForAllOutgoingChannels(cb func(*models.ChannelEdgeInfo,
 	*models.ChannelEdgePolicy) error) error {
 
 	return b.cfg.Graph.ForEachNodeChannel(b.cfg.SelfNode,
-		func(_ kvdb.RTx, c *models.ChannelEdgeInfo,
-			e *models.ChannelEdgePolicy,
+		func(c *models.ChannelEdgeInfo, e *models.ChannelEdgePolicy,
 			_ *models.ChannelEdgePolicy) error {
 
 			if e == nil {