Always provide summary for non-healthy cluster

Always provide summary for non-healthy cluster

This fixes a problem, wherein calamari does not provide
popup drill-downs for warnings or errors, should the summary
be missing.

Calamari gets health info from /api/v1/cluster/$FSID/health.
If the data here has a summary field, this summary is provided
in a popup window:

  /api/v1/cluster/$FSID/health is populated (ultimately) with
  status obtained via librados python bindings from the ceph
  cluster. In the case where there's clock skew, the summary
  field supplied by the ceph cluster is empty.

No summary field, no popup window with more health details.

Signed-off-by: Thorsten Behrens <tbehrens@suse.com>
(cherry picked from commit eaf6e0cf48488fe604d0ef0db164d44948d4e8d4)