After an extended sojourn working in the DC Extended Universe, successful filmmaker Zack Snyder casts off those studio shackles and goes full-on indie with The Last Photograph, a highly personal, long-in-gestation, self-styled Western that trades lavish studio sets for the wide-open spaces of Colombian location shoots. But while the change of pace undoubtedly felt liberating, the end result comes across as a leaden misfire. Overstuffed with pretentious symbolism and flatly delivered, vapid dialogue that constantly overstates the obvious, the ultraviolent film — about a rogue government agent who enlists the help of a heroin-addicted…