Description of problem:
In out put of ceph versions, empty list gets printed for mds but not for other daemons.

if there are no rgw/rbd-mirror daemon, ceph-version doesn't display any information (empty list) for those daemons.
only for mds, empty list gets printed if there are no mds.

Version-Release number of selected component (if applicable):
<latest>

Steps to Reproduce:
1. Configure a ceph cluster without mds and rgw, check ceph versions

Actual results:
Empty list gets printed only for mds

Expected results:
no empty list

Additional info:
(Just a enhancement request to maintain uniformity and aesthetic)