NEW YORK — The suspect in a string of at least five unprovoked knife attacks on New Yorkers was caught Wednesday night, according to police sources. They’d raced to find a masked “menace” whose rampage lasted nine days — with the suspect laughing in the face of one of the victims. “We’re going to find him and we’re going to do that with your help,” Police Commissioner Edward Caban vowed at a Wednesday evening news conference. Three victims were slashed on Wednesday morning, with that day’s rampage starting just before 7:30 a.m. near 134th Avenue and Guy R. Brewer Boulevard in Queens, according…