Retired Gen. Salvador Cienfuegos Zepeda, former defense minister, was arrested Thursday at Los Angeles International Airport on federal charges of drug trafficking and money laundering. In 2016, he denounced traffickers who had ambushed a military convoy, killing six soldiers, as “sick, insane beasts.” Now Salvador Cienfuegos Zepeda — who served as defense minister from 2012 to 2018 under then-President Enrique …