LOS ANGELES (Reuters) - Pop star Britney Spears' former confidante encouraged her to kick her drug habit five years ago, and brought drug-sniffing dogs to her Malibu home and flushed a bag of white powder down the toilet, he testified Tuesday. "She had wanted to get clean, but she was struggling with it," the former friend, Sam Lutfi, told jurors in his civil trial in Los Angeles against Spears and her parents. "I told her she needed to do it because she was the mother of two young sons... I told her that society wouldn't tolerate a mother who was abusing drugs. ...