By David Shepardson and Nora Eckert DETROIT (Reuters) -General Motors said on Wednesday it will cut U.S. electric vehicle and battery production and 1,200 factory jobs at its EV plant in Detroit, as the automaker responds to a significant slowdown in demand for its battery cars. The Detroit automaker said it will halt battery cell production at its two U.S. joint-venture battery plants - in Tennessee and Ohio - in January for about six months. It added it will temporarily lay off about 1,550 workers at t ...