In Harlem, Clean Streets For the VIP
David Gonzalez, in About New York column, notes that while hundreds of people packed Riverside Church during Pres Clinton's visit on Feb 18, there was room to spare at St Mary's Episcopal Church, where ecumenical clergy group was meeting for one of its periodic discussions about everday issues, like poverty and welfare; maintains that although their congregations share Riverside Church's neighborhood and include many people whose lives will be affected by recent policy changes, most of clergy at St Mary's were unaware that Clinton was in town; contends that like those gathered at Riverside Church, where Clinton was criticized for signing welfare law, they also say things are getting worse (M)