Police broke up an Upper East Side heroin distribution center this week, located in the rarefied real estate of 75th St. between 2nd and 3rd Aves. Neighbors seemed shocked after police broke down the door of apartment 2B at 242 East 75th, a street unfamiliar with narcotics unit raids. One said, "I was leaving my apartment [and there was a] battering ram and there were cops, so I asked some questions and I found......