fix inconsistent anonymity in grades page
fix inconsistent anonymity in grades page

closes EVAL-2682
flag=assignments_2_student

test plan:
- have a course with atleast two students
  (S1 and S2).
- create an assignment with peer reviews enabled
  and check "Peer Reviews Appear Anonymously".
- add a rubric to the assignment.
- as the teacher, assign the student
  S1 to peer review the subnmission of the
  student S2.
- as the student S2, submit to the assignment.
- still acting as the teacher, enter speedGrader
  and add feedback to the rubric.
- as the reviewing student (S1), go to the assignment
  and submit.
- then click on "Anonymous User" under peer reviews.
- fill out the rubric and add a comment.
- as the student S2 go to the "Grades" page and
  click on the rubrics toogle (first icon) for the
  assignment created.
- check that the the rubric filled by the teacher
  displays the teacher username instead of
  "Anonymous User".

Change-Id: I547f8ffb07026b236d6a20d9b9d68b4cc5a18366
Reviewed-on: https://gerrit.instructure.com/c/canvas-lms/+/304331
Tested-by: Service Cloud Jenkins <9144042a601061f88f1e1d7a1753ea3e2972119d@instructure.com>
Product-Review: Jody Sailor
Reviewed-by: Christopher Soto <fc055f1580c76dd71a51033d6c15df11032f3e31@instructure.com>
Reviewed-by: Spencer Olson <7cc0890d6f1f70810a023e7173eca5724d6c8e49@instructure.com>
QA-Review: Kai Bjorkman <4693b3d9e71784d629732770ab5e83ed8fbdb83e@instructure.com>

instructure/canvas-lms,instructure/canvas-lms,instructure/canvas-lms,instructure/canvas-lms,instructure/canvas-lms,instructure/canvas-lms,instructure/canvas-lms