fix issue where clicking 'back' from preview doesn't redirect to ember properly

fixes CNVS-13592

test plan:
  - enable draft state and quiz stats
  - as a teacher
    - create a quiz
    - preview the quiz
    - when you complete the preview it will show you preview results
    - hit the back button
    - it should redirect you back to the ember quiz overview tab for the quiz

Change-Id: I363f0dc8793e402f32b186702f30b91b721d12e8
Reviewed-on: https://gerrit.instructure.com/36386
Tested-by: Jenkins <jenkins@instructure.com>
QA-Review: Caleb Guanzon <cguanzon@instructure.com>
Reviewed-by: Jason Madsen <jmadsen@instructure.com>
Product-Review: Derek DeVries <ddevries@instructure.com>