Yet another major Wall Street firm is poised to expand outside New York City – the latest blow to the Big Apple’s tax coffers thanks to Mayor Zohran Mandani’s war on wealthy residents and businesses , The Post has learned. Private equity giant Apollo Global Management, headquartered in Manhattan, has decided to open a new business hub — internally dubbed its “second headquarters” — in either Florida or Texas with an official decision likely to be made public in the coming weeks, people close to the matter say. The new outpost could eventually become home to as many as 1,000 employees over time – in line with Apollo’s current headcount in New York, the sources said. The buyout firm currently employs more than 6,000 worldwide. Apollo is currently scouting out space in Miami and in Palm Beach, where Apollo already has a small presence, according to sources. Billionaire CEO Marc Rowan, above.…