American Airlines Inc. employees who allege their uniforms made them sick cannot seek relief against their employer in federal court, a judge held.In a written opinion this week, U.S. District Judge John J. Tharp Jr. did not rule on the merits of the allegation that chemicals in the synthetic materials used to make certain American uniforms cause migraines, skin rashes, respiratory disorders and other ailments.But Tharp held state workers’ compensation laws offer the exclusive remedy against the airline for …