Thousands of workers, union members and activists are expected to flood downtown Los Angeles on Friday for May Day , with organizers urging supports to skip work, school and shopping as part of a broader “economic blackout.” The main rally is scheduled to begin at 10 a.m. at MacArthur Park , followed by a march to Grand Park after a speaking program. Labor and immigrant rights groups say the demonstrations are part of International Workers’ Day, with similar events planned across California calling for expanded worker protections and immigrations reforms. Activists taking part in May Day protests are expected to flood downtown Los Angeles Friday. Getty Images Labor and immigrant rights groups say the demonstrations are part of International Workers’ Day.…