An LIRR rider was slashed in the face on a train in Queens on Monday in a horrifying, caught-on-video attack — days after an armed straphanger launched violence that ended with himself shot in the head. Monday’s crime occurred when a 27-year-old man tried to board a Long Island Rail Road train at the Locust Manor station around 3:50 p.m. and a 32-year-old male suspect was blocking the entrance, a witness told ABC. The victim asked the guy to move and was able to eventually board the train. But he was soon approached by the suspect, who asked him if...