The group behind the effort to build a massive video slots and entertainment complex on New York Avenue in Northeast D.C. is making a slight retreat as it has withdrawn about 10% of the 3,800-some petitions submitted to get a measure approving D.C. gambling on the Nov. 2 ballot. The Post reports that the group’s lawyer, John Ray, listed 389 petitions that the initiative’s pushers “would like to withdraw.” Three petition circulators told the D.C….