Impossible to use S3 Storage Backend for Gnocchi

Issue

• We can't provision S3 storage backend for Gnocchi from Director OSP 13.

• The file /usr/share/openstack-tripleo-heat-templates/puppet/services/gnocchi-api.yaml say that GnocchiBackend parameter can take s3 value but in the controller, the puppet file /etc/puppet/modules/tripleo/manifests/profile/base/gnocchi/api.pp doesn't authorize s3 backend for gnocchi_backend.