By Amanda Ferguson BELFAST (Reuters) -Northern Ireland’s biggest public sector strike in a generation shut schools, halted transport services and left icy roads ungritted in sub-zero temperatures on Thursday, with people warned to only travel or seek medical help in an emergency. Unions representing around 170,000 of the region’s 225,000 public sector workers called the 24-hour strike after failing to receive pay increases despite multi-decade high inflation, following the collapse of the region’s power-sharing government in early 2022. Car drivers beeped horns in support of workers at picket …