mon: default ceph_health_raw to json
mon: default ceph_health_raw to json

During the first iteration, the command won't return anything, or can
simply fail and might not return a valid json structure. Ansible will
fail parsing it in the filter `from_json` so let's default that variable
to empty dictionary.

Signed-off-by: Sébastien Han <62d754cc350e84d3b1c32ae79f976f5348e74a40@redhat.com>

fgal/ceph-ansible,ceph/ceph-ansible,ceph/ceph-ansible,fgal/ceph-ansible