dns: forwarding: T2900: restore proper Config() level in verify()
dns: forwarding: T2900: restore proper Config() level in verify()

Despite the fact that running verify on Config() is "bad" and "not as intended"
the level of the configuration must match the keys that are checked by exits().

Re-set proper Config() level before querying the system nodes.

vyos/vyos-1x,vyos/vyos-1x,vyos/vyos-1x,vyos/vyos-1x