Course created event is triggered too late

Discovered while working on MDL-44640
in funciton create_course() \core\events\course_created is triggered after we add blocks, enrolment instances, etc.

This may be good for event observers but in the logs it will look like we first create enrolment instances for some course and THEN create a course itself.

I had to adjust unit tests in MDL-44640 because the course_created event is no longer the first one in the sink after creating the course.