Don't override content_item in the AdvancedSearchFinderApi
Don't override content_item in the AdvancedSearchFinderApi

The FinderApi class was changed to have a content_item method, but
this didn't work for the AdvancedSearchFinderApi class as it was still
handling it as an attribute.

Remove the attr_reader, and attempt to cleanup the naming in the
content_item_with_search_results method.

alphagov/finder-frontend,alphagov/finder-frontend,alphagov/finder-frontend,alphagov/finder-frontend