LOS ANGELES — Former UFC heavyweight champion Brock Lesnar has informed the mixed martial arts promotion that he is retired from competition. The UFC confirmed Lesnar’s decision Wednesday. The decision doesn’t affect Lesnar’s professional wrestling career, where he has spent most of the past five years. He returned from a 4 1/2-year MMA absence last July to beat Mark Hunt at UFC 200, but the result was overturned after Lesnar failed two doping tests.