All setUp(), tearDown(), setUpBeforeClass() and tearDownAfterClass()
must, always, call to parent, to ensure that everything is properly
set and cleaned.
While in a lot of situations this is not needed (parents may not
have anything to run), with PHPUnit >= 10 this can become more
important because we are going to move the reset code from current
placement @ runBare() to setUp()/tearDown().
Note that all the changes performed in this commit have been detected
and fixed by moodle-cs (ParentSetUpTearDownSniffTest).
This patch prevent dropping an activity with delegated sections inside
another delegated section. Without this patch the teacher can create a
deadlock drag&droping the subsection inside itself. We won't allow
subsections inside subsections so any activity with subsection cannot
be dropped inside a subsección.
Andrew Nicols