Irate callers to Chuy Gomez’s morning show on 106 KMEL did the hatchet job on famed East Coast rapper Jay-Z, whose much-anticipated concert with R&B megastar Mary J. Blige did not go down at Oakland’s Oracle Arena last night. Due to technical difficulties with production — according to concert promoters and Oracle Arena’s Web site — the show had to be rescheduled for tonight at 7:30 p.m. ; all tickets for April 20th will be honored for the April 21st performance.