WASHINGTON - People connected to the Maryland racing industry - owners, trainers, breeders, employees, and fans - are in a state of shock and disbelief. For years, they hoped that the legalization of slot machines would rescue the suffering sport; on Election Night they celebrated the passage of a referendum that approved slots and channeled money into racing purses. And then last week Marylanders learned the stunning news that the owner of Laurel Park and Pimlico failed to post the requisite $28.5 million payment before the deadline to obtain a license.