Federal Realty Investment Trust is tightening its grip on the Rockville Pike retail scene. The company just paid $72.3 million for the Congressional North shopping center, adding another major piece of property to a portfolio that already includes Pike & Rose, Federal Plaza, Montrose Crossing and Congressional Plaza. Congressional North — home to Michaels, Petco, Five Below, Aldi and Restoration Hardware’s RH Outlet — sits right next door to Congressional Plaza, meaning that Federal now controls an uninterrupted stretch of property directly across the street from Wegmans. Meanwhile, the company has been shedding its holdings further north. In downtown Rockville, it offloaded The Square in…..