Now that 11 years have passed since “The Hunger Games” first hit theaters, it’s impossible to spoil these movies anymore. So, I can reveal to you without any shame whatsoever that in the fifth film of the franchise, “The Hunger Games: The Ballad of Songbirds and Snakes,” a bunch of teens kill a bunch of other teens. Shocking, I know. But this time, to up the ante, the story does double duty as a Katniss-free prequel about how the villainous president of Panem, Coriolanus Snow (Tom Blyth), became so heartless.