Collect: Repeat instances not removed after repeat_count was reduced

As I wrote in Getting more repeat instances than expected when submitting from Collect - #7 by LN

I think a good next step would be to see whether there's a logical and reasonable way to get the behavior achieved with the inner group with relevance without having to do a form design trick. I'm not sure how feasible that is. The core team won't have time to prioritize this in the short term but it would be a welcome contribution.