routing+autopilot: rename mission control store var

To clearly separate the mission control DB store (which for now will
remain kvdb only) from the graph store, we rename the `graphBackend`
variable to `mcBackend` in the `testGraphInstance` struct.

routing/pathfind_test.go

@@ -212,7 +212,7 @@ func parseTestGraph(t *testing.T, useCache bool, path string) (
 	testAddrs = append(testAddrs, testAddr)
 
 	// Next, create a temporary graph database for usage within the test.
-	graph, graphBackend, err := makeTestGraph(t, useCache)
+	graph, mcBackend, err := makeTestGraph(t, useCache)
 	if err != nil {
 		return nil, err
 	}
@@ -413,7 +413,7 @@ func parseTestGraph(t *testing.T, useCache bool, path string) (
 
 	return &testGraphInstance{
 		graph:      graph,
-		graphBackend: graphBackend,
+		mcBackend:  mcBackend,
 		aliasMap:   aliasMap,
 		privKeyMap: privKeyMap,
 		channelIDs: channelIDs,
@@ -482,7 +482,7 @@ type testChannel struct {
 
 type testGraphInstance struct {
 	graph     *graphdb.ChannelGraph
-	graphBackend kvdb.Backend
+	mcBackend kvdb.Backend
 
 	// aliasMap is a map from a node's alias to its public key. This type is
 	// provided in order to allow easily look up from the human memorable alias
@@ -750,7 +750,7 @@ func createTestGraphFromChannels(t *testing.T, useCache bool,
 
 	return &testGraphInstance{
 		graph:      graph,
-		graphBackend: graphBackend,
+		mcBackend:  graphBackend,
 		aliasMap:   aliasMap,
 		privKeyMap: privKeyMap,
 		links:      links,

routing/router_test.go

@@ -123,7 +123,7 @@ func createTestCtxFromGraphInstanceAssumeValid(t *testing.T,
 	mcConfig := &MissionControlConfig{Estimator: estimator}
 
 	mcController, err := NewMissionController(
-		graphInstance.graphBackend, route.Vertex{}, mcConfig,
+		graphInstance.mcBackend, route.Vertex{}, mcConfig,
 	)
 	require.NoError(t, err, "failed to create missioncontrol")