SCOTTSDALE, Ariz. –– Last week, Gavin Stone was shaping up to be the feel-good story of Dodgers spring training. Now, he has suffered a “disappointing” setback that raises renewed questions about the Dodgers’ opening day rotation. As manager Dave Roberts announced Monday morning, Stone’s surgically repaired shoulder “flared up” on him last week, after the 27-year-old made his long-awaited return from an injury that sidelined him for all of last year. In his Feb. 24 outing, Stone looked