Sing it with us: “Thunder! (ah-ah, ah-ah-ah) .” As Season 3 of Netflix’s “America’s Sweethearts: Dallas Cowboys Cheerleaders” premieres today, fans are getting an even closer look at the discipline, glamour and preparation behind one of America’s most iconic squads. But while the Dallas Cowboys Cheerleaders are known for their polished, camera-ready appearance, the beauty philosophy behind their routine isn’t reserved for women in their 20s. In an exclusive interview with the New York Post,