LOS ANGELES — A judge allowed Britney Spears to hire an attorney of her choosing at a hearing Wednesday in which she broke down in tears after describing the “cruelty” of her conservatorship.Los Angeles Superior Court Judge Brenda Penny approved Spears hiring former federal prosecutor Mathew Rosengart, who called on Spears’ father to immediately resign as her conservator.“The question remains, why is he involved,” Rosengart said outside the courthouse.Britney Spears, taking part in the hearing by phone, told the judge she …