“I don’t care,” Anna said, as she screwed up a brown paper bag that had contained a steak and black bean Chipotle burrito. “If I die, I die.” Anna, who had wolfed down her lunch in a Manhattan branch of the fast food chain, said she would continue to visit Chipotle at least twice a week despite the Mexican grill chain having been struck by outbreaks of E coli and norovirus that left more than …