loaders: Remove the validation proxy
loaders: Remove the validation proxy

The loaders are now sending the full swh.model.model objects.

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