The grandstand at Laurel Park race track is rarely full. Current plans call for the track, which will host the Preakness Stakes this year, to be converted to a training facility, but state lawmakers want to examine the financials of that proposal. (File photo by John Rydell/Maryland Matters)A legislative panel is delaying the proposed purchase of Laurel Park by the Maryland Stadium Authority, asking for a cost-benefit review of the $48.5 million…