Remove examiners tab when the teacher is the corrector

[stmolivier]

If the teacher is the corrector (not peer mode), then when he access the drop list, there are 3 tabs : drops by default, drops awaiting and examiners.
If i click on examiner tab in that case :

No result was found for query although at least one row was expected.
500 Internal Server Error -
Stack Trace
1.in /home/Claroline/vendor/doctrine/orm/lib/Doctrine/ORM/Internal/Hydration/SingleScalarHydrator.p
hp at line 43
40. $numRows = count($data);
41. if ($numRows === 0) {
42. throw new NoResultException();
43. }
44. if ($numRows > 1 || count($data[key($data)]) > 1) {

Maybe hiding the tab in no peer mode would be useful.