TOKYO—Japan’s factory output jumped at the fastest pace on record in November, as easing global supply chain bottlenecks helped car production leap out of its recent slump, lifting prospects for a strong fourth-quarter economic rebound. But while improved manufacturing conditions provide some relief for policymakers, persistent global semiconductor shortages and new risks from the Omicron coronavirus variant are expected to cloud the outlook for the world’s third-largest economy. Factory production gained 7.2 percent in November from the previous month, posting its largest jump since 2013 when comparable data first became available, thanks to rising output of motor vehicles and plastic products. That meant production rose for the second straight month after increasing 1.8 percent in October and posted a faster rise than the 4.8 percent gain expected in a Reuters poll. “Output recovered to where it was previously because car production rebounded,” said Takeshi Minami, chief economist at Norinchukin Research …