downgrade service errors in course copies
downgrade service errors in course copies

closes FOO-1365
flag=none

TEST PLAN:
  1) hobble inst-fs so it fails
  2) run a course copy
  3) the content migration fails with error as usual
  4) sentry doesn't get notified

Change-Id: I22aff24096ca5b554b79ae201fa9b5680bb42903
Reviewed-on: https://gerrit.instructure.com/c/canvas-lms/+/255588
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>

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