After answer has been deleted: course progress not updated

[Nublert]

At least in EofAI, when an answer is deleted, the course progress view doesn't deduct the exercise from the no. of completed answers.
Also, the exercise shows as completed in the section card.

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Write test cases for the 3 broadcasts here:

https://github.com/rage/quizzes/blob/master/packages/backendv2/src/models/quiz_answer.ts#L1068-L1086