Kevin Costner says, once and for all, that he is not coming back to Yellowstone. The hit cable series finally began filming its fifth and final season recently without Costner as ranching patriarch John Dutton. Just last month, Costner signaled he would still be open to filming some sort of farewell to the show, even though production had resumed without him, telling Deadline he was “very open to coming back … if the writing’s there and I’m happy with it. I’m open to that.” But Costner also said at that time that he “took a beating over these guys not speaking up for me and allowing crazy stor…