A prolific foreign hacker behind sophisticated cyberattacks that netted an estimated $55 million was sentenced Friday to eight years in prison in rare win for law enforcement officials who have identified, but failed to arrest, hundreds of others like him. Prosecutors in federal court in Brooklyn had sought up to 14 years behind bars for Ercan Findikoglu, a Russian-speaking Turkish national so skilled with computers that he tracked the sprawling international heist in real-time to make sure a small army of thieves wouldn’t cheat him out of his share of the proceeds.