At the heart of “Vampire Academy” are two teenage girls, best friends since they were 6, who would die for each other. Unfortunately, that sometimes means literally. “The female friendship at the center is really amazing to see because so often, women are pitted against each other and we don’t get a lot of representation of beautiful, genuine female friendship,” Sisi Stringer, the 25-year-old Australian actress who stars as Dhampir Rose Hathaway, told the Daily News. “But also our friendship is at the very center of the story in terms of the dominion and the conflicts that come up inside of th…