Cruising around Caracas in a convoy with five cellphones full of valuable contacts, Gen. Manuel Cristopher Figuera displayed trappings that befitted his reputation as a loyal soldier who rose from an upbringing in a dirt-floored hut to become Venezuela’s spy chief. Now one of the most prominent defectors in two decades of socialist rule in Venezuela has come to Washington seeking revenge against his former boss. On Tuesday, he met with the U.S. special envoy to Venezuela, Elliott Abrams.