Enable setting of ceilometer as a non-root user

By adding 'become' element, you can set ceilometer as non root user.

Change-Id: I146f3aec6b1270d40c02f4f7883c169aaa796239
Closes-Bug: #1798035

ansible/roles/ceilometer/tasks/config.yml

@@ -121,6 +121,7 @@
   template:
     src: "pipeline.yaml.j2"
     dest: "{{ node_config_directory }}/{{ item.key }}/pipeline.yaml"
+  become: true
   register: ceilometer_pipelines
   when:
     - inventory_hostname in groups[item.value.group]