It’s time to go sit in the corner, Billy! Mayor de Blasio finally admitted Tuesday that his costly and controversial Renewal plan to fix nearly 100 of the city’s worst schools was a failure — pulling the plug on a years-long effort that cost taxpayers $773 million. “We did not say everything would be perfect,” the mayor said, offering a huge understatement to describe a program that saw one-quarter of its schools either closed or merged. “We said we were ready to go out there and create real investment, help kids right now, and see how many schools could really...