Ensure that policy file has correct group/mode

When the policy file is copied from the templated
file to the active file, it loses its group/mode
settings. This patch ensures that they are properly
replicated during the copy.

Change-Id: I30a371cbfd247dfaccfd6367555bf5b732eef689

handlers/main.yml

@@ -49,6 +49,9 @@
   copy:
     src: "/etc/gnocchi/policy.json-{{ gnocchi_venv_tag }}"
     dest: "/etc/gnocchi/policy.json"
+    owner: "root"
+    group: "{{ gnocchi_system_group_name }}"
+    mode: "0640"
     remote_src: yes
 
 - name: Start services