Remove reference to Distbuild type

The distbuild defined type doesn't exist since 9adc5fd7, so notifying
it results in a catalog compilation error.

Change-Id: I9ced1f198be5e653ee7da1837a2b93e5aad815e7

manifests/init.pp

@@ -200,7 +200,6 @@ class drupal (
       password => $site_mysql_password,
       host     => $site_mysql_host,
       grant    => ['all'],
-      notify   => Distbuild["distbuild-${site_name}"],
     }
   }