site.pp: Reference gateway.internal.staging's role
site.pp: Reference gateway.internal.staging's role

Related T1875

SoftwareHeritage/puppet-swh-site,SoftwareHeritage/puppet-swh-site,SoftwareHeritage/puppet-swh-site,SoftwareHeritage/puppet-swh-site,SoftwareHeritage/puppet-swh-site