By Laura Armstrong Cash-strapped Coronation Street bosses have sparked massive panic by reducing the number of stars who can appear in each storyline. Sources have revealed ITV chiefs faced with shrinking budgets are scaling down costs by adopting a “minimal” approach and cutting down on group scenes, such as those filmed in the Rovers Return. But the move has created a backlash among some of the soap’s stars – many of whom are paid by the scene. They are said to have become aware of a marked difference in the scripts last month. It comes as show bosses are also said to have slashed the number…