Grader report in AJAX mode does not display hints and and forgets the feedback

Discovered while testing MDLQA-7750
for more details see the description of the test and the comment of the tester.

1. Enable AJAX editing and quick feedback in grader report
2. Mouse cursor should change on hover of a grade
3. Teacher should be able to hover the grade and see details
4. Teacher should be able to edit grade and add feedback
5. Teacher should be able to hover the new grade and see details
6. Teacher should be able to change the overridden grade and feedback without reloading the page

The same is happening in 2.8. The qa tester in 2.8 must have missed it.