autocomplete: clear active item after selection

After an item is chosen, we should clear the selected item in the list view. The implementation is a little weird. I noticed that code was pretty old that I was editing :). This fixes a bug where the same item will be selected multiple times when it shouldn't be.
@sinan can you advise about this? I am not sure I understand about the item data path. In the case of autocomplete, i believe that the `is` operator will be sufficient to compare list items.