Double check course instance stats #1469
Description
There is a slight discrepancy between views in the numbers related to Students started the course; Students completed the course
Course instances view in the stats tab:
Example: AI in Society: https://courses.mooc.fi/manage/courses/d4e3c2b0-1cd0-404b-a398-257a418f8a8b/stats?tab=course-instances
Instance completions view:
Example: AI in Society (Bologna instance completions) https://courses.mooc.fi/manage/course-instances/af101080-a7a6-491c-af82-3e04913fc89a/completions
