A federal judge threw out a tentative $1.6 million settlement reached in a class-action lawsuit filed on behalf of customers whose credit-card information may have been exposed in a data breach at a high-end department store chain.In a written opinion Monday, U.S. District Judge Sharon Johnson Coleman also decertified a class of plaintiffs that had been provisionally approved in the suit against The Neiman Marcus Group LLC.The class included United States residents who used their credit or debit card any time from July 16, …