Don't show results for anonymous surveys

[Bjvanminnen]

When giving students surveys, we clearly state that their results will be anonymous and teachers will not be able to see them. We make sure to only show teachers aggregated results after they have responses from 5+ students. We also make sure that unlike other puzzle types, when the teacher navigates to that level we don't let them see the student's last attempt

Poorva recently realized however that teachers generally have access to their students passwords. This means they could log in as the student, and still see the last attempt (i.e. their answers). This PR makes it so that once a survey has been submitted, we won't show the previous responses anymore - even to the student who submitted them.

One remaining hole is that if you later unsubmit the survey (or unlock it in the case of a lockable level), the previously submitted answers will again be revealed. Avoiding this is difficult for the following reason:

• Right now every time you answer a question, we make a milestone request (even before you've submitted)
• This is done at least in part so that on multi-page surveys you can navigate between pages and still see your previous/yet unsubmitted responses.
• The ideal behavior would be that we show you your answer if you've changed it since you last submitted (and otherwise not), but we don't have any good way to do this.

[Bjvanminnen]

Change to this file are probably most easily viewed with whitespace diffs ignored https://github.com/code-dot-org/code-dot-org/pull/19753/files?w=1#diff-00a2cfbb66f812306b2ac0fea8473c03R15 as it's entirely wrapping things in the document.ready

[islemaster]

Awesome.