NEW YORK — Michael Bloomberg has a dramatic story to tell of New York City’s transformation should he decide to enter the presidential race. The city was in recession and reeling from the Sept. 11 terrorist attacks when Bloomberg became mayor in 2002. By the time he left three terms later, vast stretches of New York had been redeveloped, with new parks, office towers, stadiums, employers and taxpaying residents where there were once blighted properties and industrial land.