Docker Registry to use for storing function Docker images.
Values:
DOCKER_REGISTRY_UNSPECIFIED (0):
Unspecified.
CONTAINER_REGISTRY (1):
Docker images will be stored in multi-regional Container
Registry repositories named gcf.
ARTIFACT_REGISTRY (2):
Docker images will be stored in regional Artifact Registry
repositories. By default, GCF will create and use
repositories named gcf-artifacts in every region in
which a function is deployed. But the repository to use can
also be specified by the user using the
docker_repository field.
