Sorry, I’ve never been a Quentin Tarantino fan. Amid the screaming and shouting and bloodletting, I’ve mostly missed the point of his movies. But “Once Upon a Time ... in Hollywood” is different. It only feels Tarantino at the end (and oh yes, the nearly three-hour wait is worth it). Before then, we get Leonardo DiCaprio grappling with his fading stardom and Brad Pitt as his hilarious stunt double. We get a fun and tragic glimpse of 1960s Hollywood, and I say a filmmaker has found his best self in it.