SAN GABRIEL, Calif. — The aged gunman dependable for the dance corridor massacre in Monterey Park was out of action with other Asian immigrants who observed pleasure and companionship in venues like the Star Ballroom Dance Studio, previous friends mentioned. Huu Can Tran, 72, was an indignant loner who appeared to have a grudge towards the world — not just his ex-spouse — people he crossed paths with explained Tuesday. “I believe his full lifetime was going down,” reported a guy who used to lease an apartment from Tran and questioned that his name not be used for the reason that he did not want to be related with the…