Namely get_num_tracked_users and is_tracked_user()

This reverts commit d7c29c22.

Conflicts:
	version.php

Oracle is rounding numbers with no decimals - which causes a test failure.

MDL-37082 mod_assign: removed reference to deprecated delete_course_module function in the unit tests

Conflicts:
	version.php

Conflicts:
	calendar/upgrade.txt

MDL-37082 core_course: create new course_delete_module function that handles the whole deletion process

Instead of repeating code all over the place because the original function delete_course_module only partially deletes data, we now place all the functionality needed to delete a module here.

The failure was caused by a regression in MDL-37527.