refs VICE-1507
flag=deprecate_sms
test plan:
**BEFORE running migration**
- set a custom override on your root account
> account.settings[:allowed_sms_notification_categories] = 'foobar'
> account.save!
**AFTER setup**
- run migrations
- confirm that your previous setting has been removed
qa risk: low
Change-Id: Idba401d78f474e441f379c7ad173a6a65a5e119b
Reviewed-on: https://gerrit.instructure.com/c/canvas-lms/+/272556
Reviewed-by: Rob Orton <rob@instructure.com>
QA-Review: Rob Orton <rob@instructure.com>
Product-Review: Rob Orton <rob@instructure.com>
Tested-by: Service Cloud Jenkins <svc.cloudjenkins@instructure.com>