Mark Crumpacker, leader of marketing at Chipotle Mexican Grill Inc. as it tries to rebound from last year's foodborne illness outbreaks, has been indicted on a drug charge and has been placed on leave by the beleaguered Denver-based burrito chain, according to national news reports. Crumpacker -- chief marketing and development officer at Chipotle (NYSE: CMG) -- is named in a New York City indictment, unveiled Thursday, as one of 18 alleged buyers from a cocaine ring, the Wall Street Journal and…