container: Allow to use registry authentication

container: Allow to use registry authentication

The registry.redhat.io regsitry requires authentication so before pulling
the RHCS 4 container images from the registry we need to do the login
step.
This is done via the new ceph_docker_registry_auth variable. The
default value is false but true for RHCS setup.
When set to true, you need to provide the username and password
for the registry via the associated variables.
This patch also updates the ceph_docker_registry value for RHCS setup.

Closes: https://bugzilla.redhat.com/show_bug.cgi?id=1748911
Signed-off-by: Dimitri Savineau <dsavinea@redhat.com>