Update gnocchi config file permissions

Change-Id: I99908c121e10545da79cde739831cc95f6f5dd3a
Related-Prod: PROD-20751
diff --git a/gnocchi/_common.sls b/gnocchi/_common.sls
index e8413e3..43749bc 100644
--- a/gnocchi/_common.sls
+++ b/gnocchi/_common.sls
@@ -13,6 +13,8 @@
   file.managed:
   - name: /etc/gnocchi/gnocchi.conf
   - source: salt://gnocchi/files/{{ cfg.version }}/gnocchi.conf
+  - mode: 0640
+  - group: gnocchi
   - template: jinja
   - require:
     - pkg: gnocchi_common.pkgs