Add missing "become: true"

This is needed in order to manage the configuration when injecting the
certificate.

Change-Id: I75b68876a6276d2fc31b4dc675368e7caece03f5

tripleo_ansible/roles/tripleo_cephadm/tasks/monitoring.yaml

@@ -45,6 +45,7 @@
         CEPH_CONTAINER_BINARY: "{{ tripleo_cephadm_container_cli }}"
 
     - name: Config ssl cert(s) and key(s) for the exposed components
+      become: true
       block:
         - name: Get ceph_cli
           include_tasks: ceph_cli.yaml