ember: fix loading of paginated quizzes on index page

Test plan:
 - Load a quiz index page with fabulous quizzes turned on. It should
   load all the quizzes even if you have enough quizzes that it has to
   paginate (e.g. over 10)

fixes CNVS-12787

Change-Id: I5c77d12cbf31160feb705eb515c5e6ed7cff05e4
Reviewed-on: https://gerrit.instructure.com/34128
Reviewed-by: Jason Madsen <jmadsen@instructure.com>
Tested-by: Jenkins <jenkins@instructure.com>
QA-Review: Caleb Guanzon <cguanzon@instructure.com>
Product-Review: Stanley Stuart <stanley@instructure.com>