(Reuters) – “American Idol” judge and mentor Randy Jackson is leaving the Fox TV singing competition after 13 seasons, the network said on Tuesday, after the show suffered a decline in ratings in recent years. Music producer Jackson, 58, was one of the show’s original three judges along with Paula Abdul, who departed the show in 2009, and Simon Cowell, who left in 2010. Jackson left the judges’ panel after 12 seasons, but continued as […]