NEW YORK — Mayor Eric Adams’ administration has since last week reported a steady increase in migrant arrivals — even as volunteers welcoming the desperate travelers to New York City say they’re not seeing a massive influx amid a drop in U.S. southern border crossings. Molly Schaeffer, Adams’ director of asylum-seekers operations, said in a private phone briefing Thursday with local lawmakers that more than 900 migrants arrived this past Monday alone, according to a recording of the call obtained by the New York Daily News. That came on top of roughly 4,300 migrants Schaeffer said arrived last...