Kube-OVN sets a subnet's VPC (ovn-cluster when none is given), but a
subnet it hasn't processed, such as one with an invalid provider, has
none. The VPC page grouped those under "Virtual Private Cloud:" with an
empty name, and its Create Subnet, Topology and actions buttons pointed
at no VPC.
Show None as the VPC name for that group and leave out its VPC buttons.
Signed-off-by: Marcelo Fukumoto <marcelo.fukumoto@suse.com>
