fix student progression pagination

fixes CNVS-13811

test plan:
 - have a large browser window (15" full screen will do)
 - enroll 12 or more students in a course with draft state enabled
 - go to the modules page
 - click "View Progress"
 - there should be no blank space at the bottom of the
   "STUDENT PROGRESS" pane on the right
 - you should be able to scroll down and see the last few students

Change-Id: I79342288e4809d03f7c8bd07c7782310f841e8b6
Reviewed-on: https://gerrit.instructure.com/37089
Tested-by: Jenkins <jenkins@instructure.com>
Reviewed-by: James Williams  <jamesw@instructure.com>
QA-Review: Clare Strong <clare@instructure.com>
Product-Review: Jeremy Stanley <jeremy@instructure.com>