Fix Rubocop errors

app/models/geo_node_status.rb

@@ -58,14 +58,6 @@ class GeoNodeStatus
     @cursor_last_event_date = value
   end
 
-  def db_replication_lag
-    @db_replication_lag ||= Gitlab::Geo::HealthCheck.db_replication_lag
-  end
-
-  def db_replication_lag=(value)
-    @db_replication_lag = value
-  end
-
   def repositories_count
     @repositories_count ||= repositories.count
   end