Quiz: LDB requirements fix

LDB can not be required to view the results if it's not required to
actually take the quiz, as is consistent with what the setting page
shows.

Closes CNVS-4832

TEST PLAN
---- ----

  - enable LDB plugin if you need to
  - create a quiz with the LDB options checked (both to take and view
    results), and make sure it allows multiple attempts
  - save and go to the quiz page (as a teacher)
    + verify you see the LDB columns reading "Yes"
  - edit the quiz, turn off the LDB requirement to view the results
    + verify you see only the first LDB column reading "Yes"
  - turn them off completely
    + verify you see both columns reading "No"

> Student experience test

  - turn back both LDB options on
  - visit the quiz as a student in a regular browser
    + verify you can not take the quiz
  - turn both options off
    + verify you can take the quiz now
    + take it
      - verify you can see the results
  - turn back on the option to require LDB for taking the quiz
    + verify you can no longer re-take it, but can still view the
      results
  - turn back on the option to require LDB for viewing the results
    + verify you can no longer view the results either

Change-Id: Ie82a75b4d028c05d2feddaea14f638e2a82cc697
Reviewed-on: https://gerrit.instructure.com/41235
Tested-by: Jenkins <jenkins@instructure.com>
Reviewed-by: Ryan Taylor <rtaylor@instructure.com>
Reviewed-by: Derek DeVries <ddevries@instructure.com>
Product-Review: Matt Fairbourn <mfairbourn@instructure.com>
QA-Review: Matt Fairbourn <mfairbourn@instructure.com>
Product-Review: Ahmad Amireh <ahmad@instructure.com>