Landlords of rent-stabilized apartments are urging Mayor Zohran Mamdani to lobby to fix a state law they claim is keeping thousands of vacant rent-stabilized units off the market — even as the city grapples with homelessness and an affordable housing problem. The landlords’ pitch to loosen restrictions for the Big Apple’s one million rent-stabilized apartments comes after the Mamdani administration inked a new $1.86 billion contract with the city’s hotel industry to provide emergency shelter to