remove embedly

this was used by collections (which no longer exist)

Test plan:
  make sure there are no references to embedly on the account settings
  page

Change-Id: Ia599877523a26560392ca554a2e760930f65deb6
Reviewed-on: https://gerrit.instructure.com/30148
Tested-by: Jenkins <jenkins@instructure.com>
Reviewed-by: Cody Cutrer <cody@instructure.com>
Product-Review: Cameron Matheson <cameron@instructure.com>
QA-Review: Cameron Matheson <cameron@instructure.com>