Check exact array contents instead of inclusion

We're using `eq` and `match_array` in most places, but there were a few
places where we were still checking each element is included in the
array. This is a bit dangerous, because the array could have duplicate
elements, and we wouldn't detect them with `include`.

spec/models/widget/card_spec.rb

@@ -31,8 +31,7 @@ describe Widget::Card do
       card2 = create(:widget_card, header: false)
       page_card = create(:widget_card, header: false, page: create(:site_customization_page))
 
-      expect(Widget::Card.body).to include(card1)
-      expect(Widget::Card.body).to include(card2)
+      expect(Widget::Card.body).to match_array [card1, card2]
       expect(Widget::Card.body).not_to include(header)
       expect(Widget::Card.body).not_to include(page_card)
     end