By Noel Randewich and Amruta Khandekar (Reuters) – U.S. stocks ended down on Wednesday, pulled lower by megacaps and energy shares as signs of a cooling jobs market reinforced expectations that the Federal Reserve could start cutting interest rates early next year. The ADP National Employment report showed private payrolls increased by 103,000 jobs in November, below economists’ expectation of 130,000. That provided fresh evidence of labor market weakness, a day after news of a drop in October job openings. The latest employment data reinforced expectations the Fed’s rate-hike campaign is cool…