A former federal prosecutor believes former President Donald Trump’s latest effort to overturn his 34-count felony conviction in Manhattan — leveraging his partial win at the Supreme Court that presidents have immunity for official acts — has a sliver of a shot, but won’t likely succeed. That case, which found Trump guilty of falsifying business records for buying adult film star Stormy Daniels’ silence, looks all but certain now to be the only one of Trump’s four criminal cases to be decided before the election, with sentencing set for later this month. An appeal could drag the matter out. “O…