He was a little bit country; she was a little bit country. Scotty McCreery, the 17-year-old from Garner, N.C., won, but the real competition wasn’t between him and fellow Southerner Lauren Alaina, 16, of Rossville, Ga. All along, the contest was between “American Idol” past and “American Idol” present. It turned out that even after 10 seasons, with fewer frills and a different cast of judges, the ratings soared. “American Idol” is indestructible.