fix issue editing questions in question banks

fixes CNVS-11006

test plan:
  - as a teacher
    - create a question bank with more than 50 questions
    - edit a question
    - it should successfully edit the question without adding a new question
      to the bank
  - do a regression test around creating and editing questions both in and
    outside of question banks

Change-Id: Iba765cf3b5c5b2687a012e44592e47d8e3ec6716
Reviewed-on: https://gerrit.instructure.com/40260
Tested-by: Jenkins <jenkins@instructure.com>
Reviewed-by: Josh Simpson <jsimpson@instructure.com>
QA-Review: Trevor deHaan <tdehaan@instructure.com>
Product-Review: Derek DeVries <ddevries@instructure.com>