NEW YORK — A worker at a Brooklyn McDonald’s was shot in the face by a customer’s son during a wild spat over a food order, police said Tuesday. The 23-year-old employee was taking orders at the McDonald’s on Fulton St. near Throop Ave. in Bedford-Stuyvesant when a woman complained about her order about 7 p.m. Monday, cops said. An argument between the worker, the woman and her 20-year-old son quickly erupted and spilled outside and across the street, when the son suddenly pulled a gun and opened fire. The McDonald’s employee was shot in side of the neck just above the jawline, a police source…