test: fixing flaky test

Author: rpenido

src/course-unit/CourseUnit.test.tsx

@@ -714,7 +714,7 @@ describe('<CourseUnit />', () => {
     await executeThunk(editCourseUnitVisibilityAndData(blockId, PUBLISH_TYPES.makePublic, true), store.dispatch);
 
     await waitFor(async () => {
-      const problemButton = screen.getByRole('button', {
+      const problemButton = await screen.findByRole('button', {
         name: new RegExp(`problem ${addComponentMessages.buttonText.defaultMessage} Problem`, 'i'),
         hidden: true,
       });