Hawkeye and Ant-Man were in the Vanity spread shoot months ago but we haven't seen them in the trailers at all. They are credited on IMDB though. Perhaps they aren't in this Avengers movie, but they are in the next Avengers movie that will conclude the Thanos saga. They were just in the spread because the movies were shot back to back
There were some rumors going around that Hawkeye is out looking for Captain Marvel at the request of Nick Fury. Hell, maybe theres just too many characters to include in the trailers. But Hawkeye is an OG Avenger, it feels like he should be included in the promos if he's in the movie.