One of the four black youths shot by so-called subway vigilante Bernhard H. Goetz last December testified against him before a New York grand jury trying to decide whether to reopen the case, his lawyer said. Lawyer Ronald Kliegerman said his client, James Ramseur, 18, testified against Goetz for 45 minutes after being granted immunity from prosecution by Manhattan Dist. Atty. Robert Morgenthau. "His testimony contradicted Goetz's version. He said he was unaware of any attempt to rob Goetz and that he was not seated near him," Kliegerman said.