When Christian Friedel was preparing to play Rudolf Höss, the real-life Nazi commandant at Auschwitz who’s the alarmingly opaque protagonist of “The Zone of Interest,” he discovered an audio recording of Höss from the Nuremberg trials. But what made “The Zone of Interest” writer-director Jonathan Glazer, who adapted Martin Amis’ novel, think Friedel would be right for Höss? “There was …