Preview in new tabMegastars Paul McCartney and Mick Jagger, the respective faces of The Beatles and the Rolling Stones, last week reignited the decades-long rivalry between the two British supergroups.McCartney, 79, belittled the Stones by calling them a “blues cover band,” while Jagger, 78, disparaged the Fab Four for failing to play giant stadiums — in contrast to the thousands of concerts staged by the “(I Can’t Get No) Satisfaction” singer and his cronies.Fans have debated the relative