NEW YORK — A Jewish man who was bashed in the head with a metal bat by a stranger who called him a “dirty Jew” tells the New York Daily News that the hate-filled attack began when his assailant spotted him wearing a yarmulke. The 25-year-old victim, a driving instructor, was bringing a student driver to a road test on Grandview Ave. near Netherland Ave. in Mariners Harbor on Feb. 12 when the attacker — identified by police as Obadiah Lashley — spotted him around 2:30 p.m., he recalled. The instructor, who didn’t want his name published, was standing on the sidewalk waiting for the test to end …