srgb changes assignment name

fixes CNVS-12920

test plan:
  - go to srgb and select an assignment and student
  - when changing assignments ensure that name is
    correct in the "Grade For" section
  - when changing student ensure that final grade
    updates properly

Change-Id: I8620ab35f743fd192a0bfd68da96d7cf233b9d10
Reviewed-on: https://gerrit.instructure.com/34548
Reviewed-by: Cameron Sutter <csutter@instructure.com>
QA-Review: Anna Koalenz <akoalenz@instructure.com>
Product-Review: Simon Williams <simon@instructure.com>
Tested-by: Jenkins <jenkins@instructure.com>