dashboard: use existing variable to detect containerized deployment
dashboard: use existing variable to detect containerized deployment

there is no need to add more complexity for this, let's use
`containerized_deployment` in order to detect if we are running a
containerized deployment.
The idea is to use `container_exec_cmd` the same way we do in the rest of
the playbook to run the different ceph commands needed to deploy the
ceph-dashboard role.

Signed-off-by: Guillaume Abrioux <30a9df5a0293a6108675377fa1673f7aa713f915@redhat.com>

ceph/ceph-ansible,ceph/ceph-ansible