The goal is to add a behat test to verify that groups can be added in the enrol cohort for course.

QA test to be automated: MDLQA-7648

QA testing instructions

1. Create several cohorts on the site and assign some users to them
2. Create a course and add an instance of enrol_cohort, select to create a new group
3. Make sure the group was created
4. Remove a user from this cohort and Add another user to the cohort
5. Run cron
6. Make sure the correct students are enrolled in the course and assigned in the group
7. Add another instance of enrol_cohort with another cohort and without group
8. Edit the instance and select to create a new group
9. Make sure the group is created and users are added to it

Once done, please change the affected QA parent to MDLQA-5249