fix "edit syllabus description" in new course

test plan:
 - create a new course
 - go to the Syllabus tab
 - press "Edit Syllabus Description"
 - the edit button should disappear and the wiki sidebar
   should appear

fixes CNVS-11193

Change-Id: I811c865c46588b31df52efd9c3df1228c945ecbf
Reviewed-on: https://gerrit.instructure.com/30848
Tested-by: Jenkins <jenkins@instructure.com>
QA-Review: Matt Fairbourn <mfairbourn@instructure.com>
Reviewed-by: Bracken Mosbacker <bracken@instructure.com>
Product-Review: Bracken Mosbacker <bracken@instructure.com>