With the pandemic receding, children back in school and businesses telling employees to return to the office, the companies that own big office buildings were hoping to move on this fall from a nightmarish two years. Instead, things got worse. More office workers are back at their desks than a year ago, but attendance at office buildings in New York, Boston, Atlanta, San Francisco and other cities is languishing well below prepandemic levels. As leases come up for renewal, companies are often opting for smaller offices, saddling landlords with millions of square feet in vacant space. And more space is expected to hit the market in the coming months as…