CLONE - A teacher can set repeated chat times

1. Login as a teacher, update a chat activity and set repeat sessions at the same time every day.
2. Check that next scheduled chat session appears in the course calendar.
3. Update a chat activity and set repeat sessions at the same time every week.
4. Check that next scheduled chat session appears in the course calendar.

Note: Only the next scheduled chat session should appear in the course calendar and not every session.