Fix lints since eslint-plugin-ember was upgraded

Author: NullVoxPopuli

tests/helpers/destroy-app.js

@@ -1,5 +1,6 @@
 import { run } from '@ember/runloop';
 
 export default function destroyApp(application) {
+  // eslint-disable-next-line ember/no-runloop
   run(application, 'destroy');
 }

tests/helpers/start-app.js

@@ -5,6 +5,7 @@ import { run } from '@ember/runloop';
 export default function startApp(attrs) {
   const attributes = Object.assign({}, config.APP, attrs); // use defaults, but you can override;
 
+  // eslint-disable-next-line ember/no-runloop
   return run(() => {
     const application = Application.create(attributes);
     application.setupForTesting();