When exactly does “if at first you don’t succeed …” morph into the proverbial “definition of insanity?” For Jersey City officials, still winless in their legal skirmishes over their attempts to fire police officers who test positive for cannabis, the answer is “not yet.” The Civil Service Commission Wednesday upheld the Office of Administrative Law’s decision to granting summary judgment to Police Officer Mackenzie Reilly and ordered the city to immediately reinstate him with back pay. “(Jersey City’s) exceptions are essentially a regurgitation of challenges in several prior similar matters,…