Drop city_style citizens_graphic_alt
City style has citizens_graphic and citizens_graphic_alt that are currently unused. As I'm looking in to really taking them in to use in https://www.hostedredmine.com/issues/683532. What's already obvious is that having the _alt tag just makes things over complicated. If the main tag for the style cannot be find, let's fallback directly to the default (not style specific) tag, and then to _alt version of that.