When using persistent grades, any change to the grades profile in Studio results in a grades recalculation.
This PR fixes an exception caused by a missing setting in the cms envs, which prevents the grades recalculating, e.g.:
Cannot grade student 2 in course course-v1:... because of exception: 'Settings' object has no attribute 'GENERATE_PROFILE_SCORES'
*JIRA tickets*: SE-1076
*Sandbox URL*: TBD - sandbox is being provisioned.
1. Enable persistent grades.
1. Create a course and enroll some users.
1. Modify the grades policy.
Watch the logs to see that grades are recalculated without error.
[ ] OpenCraft TBD
[ ] edX reviewer[s] TBD