LOS ANGELES—On the day Los Angeles City Councilman Mark Ridley-Thomas is scheduled to be arraigned on federal bribery and conspiracy charges, his council colleagues will vote Oct. 20 on whether to immediately suspend him from office. The motion to suspend Ridley-Thomas, 66, was introduced by Council President Nury Martinez and seconded by Councilman Mitch O’Farrell, the council president pro tem. The vote is scheduled as a special meeting at 11:15 a.m. Wednesday, amid the council’s regular 10 a.m. meeting. “The trial on the indictment has yet to take place and a person is presumed innocent until proven guilty; however, a council member who has been charged with public corruption cannot continue to exercise the powers of city office and preserve public trust,” the motion states. Ridley-Thomas told his colleagues on Monday that he will “immediately step back” from participating in council and committee meetings, but he intends to remain in …