Revert "chainntnfs/btcdnotify: disable height hint cache in testing"

This reverts commit 98e7c968d4.

chainntnfs/btcdnotify/btcd_test.go

@@ -23,7 +23,7 @@ func initHintCache(t *testing.T) *chainntnfs.HeightHintCache {
 	if err != nil {
 		t.Fatalf("unable to create db: %v", err)
 	}
-	hintCache, err := chainntnfs.NewHeightHintCache(db, true)
+	hintCache, err := chainntnfs.NewHeightHintCache(db)
 	if err != nil {
 		t.Fatalf("unable to create hint cache: %v", err)
 	}