A woman voted Miss Clackamas County in 2006 is sentenced to 20 years in prison in connection with the death of a five-year-old girl. Guadalupe Quintero, 24, of Gresham pleaded guilty yesterday to manslaughter for aiding and abetting her boyfriend's torture of his young daughter over a period of several years, leading to her death.   The girl, who weighed 28 pounds when police arrived at the couple's residence last April, had numerous broken bones and was malnourished, and was pronounced dead after she was taken to a Portland hospital. Quintero's boyfriend, Christopher Rosillo, 24, is scheduled to plead guilty later this week to murder by torture and abuse.