* cni: ensure to setup CNI addresses in deterministic order
Currently as commented in the code the go-cni library returns an unordered map
of interfaces. In cases where there are multiple CNI interfaces being created this
creates a problem with service registration and healthchecking because the first
address in the map is being used.
The use case we have where this is an issue is that we run CNI with the macvlan
plugin to isolate workloads, but they still need to be able to access the host on
a static address to be able to perform local resolving and hit host services like
the Consul agent API. To make this work there are 2 options, you either add a
macvlan interface on the host with an assigned address for each VLAN you have or
you create an additional veth bridged interface in the container namespace.
We chose the latter option through a custom CNI plugin but the ordering issue
leaves us with incorrect service registration.
* Updates after feedback
* First check for the CNIResult interfaces length, if it's zero we don't need to proceed
at all.
* Use sorted interfaces list for the address fallback scenario as well.
* Remove "found" log message logic, when an address isn't found an error is returned stating
the allocation could not be configured as an address was missing from the CNIResult. If we
still need a Warn message then we can add it to the condition that returns the error if no
address could be found instead of using the "found" bool logic.
