Remove host option

Update cinder backend config for ceph,
backend parameter "host" has been deprecated starting from Kilo,
and changed to "backend_host", and, since Pike, it was removed
completely.

Change-Id: I7c20d6cfd32fa37c9bfe33d0938f71e5afb73c64
Related-Prod: PROD-22192 (PROD:22192)
diff --git a/tests/pillar/ceph_single.sls b/tests/pillar/ceph_single.sls
index 761943b..c12365b 100644
--- a/tests/pillar/ceph_single.sls
+++ b/tests/pillar/ceph_single.sls
@@ -4,6 +4,7 @@
     version: liberty
     backend:
       ceph_backend:
+        backend_host: ceph
         type_name: standard-iops
         backend: ceph_backend
         pool: volumes
@@ -58,6 +59,7 @@
     version: liberty
     backend:
       ceph_backend:
+        backend_host: ceph
         type_name: standard-iops
         backend: ceph_backend
         pool: volumes