NEW YORK — Startling video shows a group of NYPD cops being attacked by migrants at a shelter on Randall’s Island. Migrants surrounded about five uniformed officers and threw bottles and debris at them as the cops tried to apprehend a disorderly man inside the shelter last Thursday, the video shows. At one point, someone hurls a backpack, striking a cop in her head with it. A few moments later, a shelter resident with crutches tries to poke an officer. Shelter residents are seen screaming at the officers in Spanish. Cops are holding up their batons to deflect the objects being thrown at them. …