A rabbi who alleges Cozen O’Connor helped his congregation of almost 40 years cheat him out of half his deferred compensation has successfully blocked the firm from obtaining privileged documents from his attorneys.In a written opinion Wednesday, U.S. Magistrate Judge Gabriel A. Fuentes quashed subpoenas Cozen served on two lawyers who used to represent Rabbi Stanley Kroll and the law firm that currently represents him in his lawsuit against the firm.The subpoenas sought certain documents concerning the lawyers&rsquo …