bgpd: Do not ignore auto generated VRF instances when deleting

bgpd: Do not ignore auto generated VRF instances when deleting

When VRF instance is going to be deleted inside bgp_vrf_disable(), it uses
a helper method that skips auto created VRF instances and that leads to STALE
issue.

When creating a VNI for a particular VRF vrfX with e.g. `advertise-all-vni`,
auto VRF instance is created, and then we do `router bgp ASN vrf vrfX`.

But when we do a reload bgp_vrf_disable() is called, and we miss previously
created auto instance.

Signed-off-by: Donatas Abraitis <donatas@opensourcerouting.org>