At a sentencing that took only minutes, the military judge, Col. Jeffery R. Nance of the Army, also reduced Sergeant Bergdahl’s rank to private and required him to forfeit $1,000 a month of his pay for 10 months. Prosecutors had sought 14 years in a military prison. President Trump, who has labeled Sergeant Bergdahl a “dirty rotten traitor,” quickly criticized Friday’s sentence, calling it “a complete and total disgrace to our Country and to our Military.”