For Donald J. Trump, it is a long-held legal strategy, if not a point of pride, to avoid knuckling under to plaintiffs in court. “I don’t settle lawsuits — very rare — because once you settle lawsuits, everybody sues you,” he said recently. But Mr. Trump made an exception when buyers of units in Trump SoHo, a 46-story luxury condominium-hotel in Lower Manhattan, asserted that they had been defraud