NEW YORK — Lev Parnas once pitched himself in TV interviews and through an unorthodox publicity campaign by his lawyer as someone who could expose corruption in the Trump administration over its dealings in Ukraine.Less than two years later and with less fanfare, the 49-year-old is going on trial in a federal case that makes him out to be more of an ordinary grifter than a whistleblower who would bring down former President Donald Trump and Rudy Giuliani.Jury selection is scheduled to begin Tuesday in a trial in which …