Bloomberg's @markgurman says hiring John Giannandrea to lead Apple's AI team has been the biggest mistake of Tim Cook's career at Apple: "In 2018, they hired John Giannandrea. He was this high flyer at Google. He ran AI in search, and Apple thought they would hire this guy and really hit the ground running and be at the forefront of AI." "Just seven years earlier, they announced Siri in 2011. There was absolutely nothing like it. It was a breakthrough. But then it became utter junk." "You…