provider/ec2: re-enable race test
provider/ec2: re-enable race test

Fixed LP 1519141

waigani/juju,mjs/juju,alesstimec/juju,dooferlad/juju,dooferlad/juju,gabriel-samfira/juju,axw/juju,AdamIsrael/juju,alesstimec/juju,reedobrien/juju,mikemccracken/juju,frankban/juju,anastasiamac/juju,frankban/juju,bz2/juju,bz2/juju,marcmolla/juju,reedobrien/juju,mikemccracken/juju,dimitern/juju,macgreagoir/juju,perrito666/juju,bac/juju,mikemccracken/juju,alesstimec/juju,ericsnowcurrently/juju,howbazaar/juju,AdamIsrael/juju,macgreagoir/juju,gabriel-samfira/juju,kat-co/juju,alesstimec/juju,axw/juju,perrito666/juju,dimitern/juju,bac/juju,howbazaar/juju,kat-co/juju,howbazaar/juju,waigani/juju,mikemccracken/juju,alesstimec/juju,dooferlad/juju,reedobrien/juju,mjs/juju,anastasiamac/juju,perrito666/juju,marcmolla/juju,gabriel-samfira/juju,ericsnowcurrently/juju,bz2/juju,bac/juju,gabriel-samfira/juju,mikemccracken/juju,kat-co/juju,anastasiamac/juju,reedobrien/juju,dooferlad/juju,marcmolla/juju,mjs/juju,bac/juju,ericsnowcurrently/juju,bz2/juju,axw/juju,marcmolla/juju,gabriel-samfira/juju,howbazaar/juju,AdamIsrael/juju,perrito666/juju,bz2/juju,ericsnowcurrently/juju,kat-co/juju,axw/juju,mjs/juju,macgreagoir/juju,macgreagoir/juju,perrito666/juju,waigani/juju,reedobrien/juju,dimitern/juju,marcmolla/juju,bac/juju,frankban/juju,ericsnowcurrently/juju,macgreagoir/juju,howbazaar/juju,mjs/juju,mjs/juju,anastasiamac/juju,AdamIsrael/juju,waigani/juju,dooferlad/juju,frankban/juju,anastasiamac/juju,mjs/juju,dimitern/juju,frankban/juju,dimitern/juju,kat-co/juju,axw/juju