core: Report unreachable domain names when setting host as non operational

When setting a host as non operational because an error reaching one
storage domain, the audit log will now report the name of the unreachable
storage domains

Change-Id: I6b68d1c2a387c84e97137b27f00956870fd96357
Signed-off-by: Tal Nisan <tnisan@redhat.com>
Bug-Url: https://bugzilla.redhat.com/1116820