Do not implicitly set values in clean function

[jooooosef]

        if self.cleaned_data.get("type") in [QuestionType.TEXT, QuestionType.HEADING]:
            self.cleaned_data["allows_additional_textanswers"] = False
            self.cleaned_data["counts_for_grade"] = False

in evap/staff/forms.py
Why are we setting these values here? I would think that we should check that these are indeed set to False because the frontend should enforce that. Maybe not something for this issue, but we shouldn't just ignore it if a True value falls in here

Originally posted by @niklasmohrin in #2450 (comment)

[ybrnr]

As discussed with @jooooosef and @niklasmohrin this is implemented in #2450. So can someone unassign me please? :)