Minor fixes based on lgtm.com alerts (#6819)

* Remove a couple of superfluous trailing arguments

* Simplify assignment logic in a couple of places

* Modify some potentially inconsistent setState calls to use the function form

* Fix eslint errors

webapp/components/admin_console/push_settings.jsx

@@ -79,8 +79,6 @@ export default class PushSettings extends AdminSettings {
             agree = true;
         } else if (config.EmailSettings.PushNotificationServer === Constants.MTPNS) {
             pushNotificationServerType = PUSH_NOTIFICATIONS_MTPNS;
-        } else {
-            pushNotificationServerType = PUSH_NOTIFICATIONS_CUSTOM;
         }
 
         let pushNotificationServer = config.EmailSettings.PushNotificationServer;