[C2] Deleting test does not orphan questions

[ywarnier]

• As a teacher
• When I create a course "ABC"
• And I follow "Exercises"
• And I create a new test "Test1"
• And I create a question "Question1"
• And I return to Exercises list
• And I delete "Test1"
• And I go to the questions bank
• Then I should see "Orphan question". I don't, the question is still associated with Test1

Also, Test1 still appears in c_quiz, resource_node and resource_link. Removing Test1 from those tables manually does automatically make Question1 an orphan.

[christianbeeznest]

It is checked with this commit 2a15c92

Thanks for confirmation