Voters in a handful of City Council districts face a deadline in choosing their candidates, if they haven’t already voted by mail or in-person at an early voting location. Polls close at 8 p.m. next Tuesday (Sept. 12) in the preliminaries for District 3 (Dorchester and the South End), District 5 (Hyde Park, Mattapan and Roslindale), District 6 (Jamaica Plain and West