test students will have deleted comments
test students will have deleted comments

closes FOO-1178
flag=none

TEST PLAN:
  1) make a submission comment on a submission.
     Job will get enqueued to build stream items.
  2) delete the submission (before the job runs,
     probably want jobs paused or down)
  3) run jobs, error should get logged in job log
     but not sent to sentry or error report.

Change-Id: I7affd2479bf5e8fbb0173bae3f345ee6ad730348
Reviewed-on: https://gerrit.instructure.com/c/canvas-lms/+/252269
Tested-by: Service Cloud Jenkins <9144042a601061f88f1e1d7a1753ea3e2972119d@instructure.com>
Reviewed-by: Simon Williams <088e16a1019277b15d58faf0541e11910eb756f6@instructure.com>
QA-Review: Simon Williams <088e16a1019277b15d58faf0541e11910eb756f6@instructure.com>
Product-Review: Simon Williams <088e16a1019277b15d58faf0541e11910eb756f6@instructure.com>

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