The Federal Reserve said Thursday it has ceased enforcement action against Santander Holdings USA Inc. and Santander Consumer USA. The action, issued in March 2017, was the last of three written agreements the U.S. arm of Spain’s Banco Santander had to settle with the Federal Reserve. In this case, the Federal Reserve Bank of Boston ordered Santander U.S., the Boston-based holding company, to strengthen its oversight of the $64 billion-asset Santander Consumer, its Dallas-based auto lending unit.