They don’t call Las Vegas the ‘Fight Capital of the World’ for nothin.   Next Saturday, Las Vegas will host UFC 306 at the Sphere while  Canelo Alvarez and  Edgar Berlanga  fight for the super middleweight WBC, WBO and WBA boxing titles three miles away at T-Mobile Arena.  Both events take place on Mexican Independence Day weekend.     Bantamweight champion  Sean O’Malley headlines the UFC 306 fight card in the historic event at the high-tech venue against top contender  Merab Dvalishvili .