Config plugin: return EmptyModlist when no change is applied

When ipa config-mod is called with the option --enable-sid,
the code needs to trap EmptyModlist exception (it is expected
that no LDAP attribute is modified by this operation).
The code had a flaw and was checking:
    'enable_sid' in options
instead of
    options['enable_sid']

"'enable_sid' in options" always returns true as this option
is a Flag with a default value, hence always present even if
not specified on the command line.

Fixes: https://pagure.io/freeipa/issue/9063
Reviewed-By: Rob Crittenden <rcritten@redhat.com>

ipaserver/plugins/config.py

@@ -707,7 +707,7 @@ class config_mod(LDAPUpdate):
         if (isinstance(exc, errors.EmptyModlist) and
                 call_func.__name__ == 'update_entry' and
                 ('ca_renewal_master_server' in options or
-                 'enable_sid' in options)):
+                 options['enable_sid'])):
             return
 
         super(config_mod, self).exc_callback(