A state Supreme Court judge ruled in the city’s favor to block arbitration over the “minimum manning” clause in its labor contract with the firefighters, which requires 15 firefighters must be on duty at all times. It’s been the main sticking point during the city’s 3½-year contract stalemate with the Watertown Professional Fire Fighters Association Local 191. Union President Daniel Daugherty confirmed Tuesday morning that Judge James P. McClusky ruled against the firefighters by granting a permanent stay of arbitration. City Manager Sharon A. Addison said she was “very pleased” with Judge McClusky’s decision. “I’m elated,” she said. “I mean, we’ve fought long and hard for what is in the best interest of the city.”