Store and retrieve avatars in/from LDAP exclusively

No need to keep them in two places at the same time. We can fetch them
from LDAP whenever we want to do something with them.

app/controllers/admin/users_controller.rb

@@ -20,6 +20,8 @@ class Admin::UsersController < Admin::BaseController
     end
 
     @services_enabled = @user.services_enabled
+
+    @avatar = LdapManager::FetchAvatar.call(cn: @user.cn, ou: @user.ou)
   end
 
   private