The get_course_members API returns a dict of users associated with a course.
This is a potentially expensive operation on a large course, so there is a
control in place to limit its cost.  If a course has more than
settings.COURSE_MEMBER_API_ENROLLMENT_LIMIT enrollments, then the function
raises an OverEnrollmentLimitException.

This API was added to help implement the LTI 1.3 Names and Roles Provisioning
service.

Jira references: [BD-24] [BB-2726] [TNL-7330] 
Pull request: #25843
Co-authored-by: Giovanni Cimolin da Silva <giovannicimolin@gmail.com>