multi: fix make lint

Fixes new lint errors caught by the latest version.

lncfg/monitoring_on.go

@@ -6,7 +6,7 @@ package lncfg
 // Prometheus is the set of configuration data that specifies the listening
 // address of the Prometheus exporter.
 //
-// nolint:lll
+//nolint:lll
 type Prometheus struct {
 	// Listen is the listening address that we should use to allow the main
 	// Prometheus server to scrape our metrics.