RALEIGH, N.C. — A North Carolina judge was scheduled to hear arguments Tuesday into declaring the Republican in the country’s last undecided congressional race the winner despite an investigation into whether his lead was boosted by illegal vote-collection tactics. A trial judge in the state capital was expected to hear lawyers for candidate Mark Harris argue that the now-disbanded elections board was supposed to have declared him the winner in November, delayed acting to sort out ballot-fraud allegations, and now can’t certify him as the winner.