Michael Cohen hasn’t even taken the stand in former President Donald Trump’s trial, and his credibility — already under scrutiny due to his history of lying under oath — was questioned during another witness’ testimony. David Pecker, former National Enquirer publisher, made several statements during his testimony last week that indicated his belief that Cohen was less than reliable. Pecker agreed that Cohen, Trump’s former personal attorney, was “prone to exaggeration.” The remarks exacerbate existing concerns Trump’s attorney’s have voiced about the credibility of Cohen, who has admitted to l…