Adding assert to check for python-passlib on control host

roles/openshift_metrics/tasks/main.yaml

@@ -1,4 +1,12 @@
 ---
+- local_action: shell rpm -q python-passlib || echo not installed
+  register: passlib_result
+
+- name: Check that python-passlib is available on the control host
+  assert:
+    that:
+      - "'not installed' not in passlib_result.stdout"
+    msg: "python-passlib rpm must be installed on control host"
 
 - name: Set default image variables based on deployment_type
   include_vars: "{{ item }}"