CANNES, France — The euphoric “Leto,” shown in Cannes a few years ago (and a film everyone in the press room could agree on), “Petrov’s Flu,” in 2021, a hard-to-follow angsty dream of a movie which you might better enjoy on LSD and if you don’t do LSD then it’s OK because watching it will make you feel like you’re on it and this year in Cannes, “Tchaikovsky’s wife” (“Zhena Chaikovskogo” in the original Russian) a period piece shown from