Explicitly require wsgi to be enabled in apache2

PROD-32552

Change-Id: I027ffc35c5a09081a8bd565067cdea234e054666
diff --git a/apache/server/site/gnocchi.yml b/apache/server/site/gnocchi.yml
index 7aaba6f..785f6f2 100644
--- a/apache/server/site/gnocchi.yml
+++ b/apache/server/site/gnocchi.yml
@@ -9,6 +9,10 @@
     apache_gnocchi_api_port: 8041
   apache:
     server:
+      enabled: true
+      default_mpm: event
+      modules:
+        - wsgi
       site:
         gnocchi:
           enabled: false