preflight check should complain if network setup is incomplete

During RSS, I uploaded a config file for london to switch 14.

That file contained this config

# TODO: docs on network config
[rack_network_config]
infra_ip_first = "172.20.15.25"
infra_ip_last = "172.20.15.32"
bgp = []


[rack_network_config.switch0.qsfp0]
routes = [ ]
addresses = [ ]
uplink_port_speed = "40G"
uplink_port_fec = "none"
autoneg = true
bgp_peers = []

# The one routed through lab `172.20.27.0/24`
[rack_network_config.switch1.qsfp0]
routes = [ { nexthop = "172.20.15.25", destination = "0.0.0.0/0" } ]
addresses = [ {address = "172.20.15.29/29" } ]
uplink_port_speed = "40G"
uplink_port_fec = "none"
autoneg = true
bgp_peers = []

So, no actual network routes/addresses for switch 0.

I then ran preflight check, and it went ahead and tried to configure that address, and things failed:

alan@jeeves $ ssh -t wicket@fe80::aa40:25ff:fe05:2702%london_sw0tp0 preflight uplink
Warning: Permanently added 'fe80::aa40:25ff:fe05:2702%london_sw0tp0' (ED25519) to the list of known hosts.
✔ Configuring switch (11.398809ms)
    configured Qsfp(Qsfp("qsfp0"))/0: ips [], routes []
✔ Waiting for L1 link up (1.004374661s)
    missing metadata
✔ Configuring IP address in host OS (37.391µs)
    configured uplinks/qsfp0_0
✔ Configuring routing in host OS (35.097µs)
    added routes []
  Checking for external DNS connectivity (60.121132165s)
    DNS server 1.1.1.1 A query attempt 1: failed to look up ntp.eng.oxide.computer: proto error: io error: No route to host (os error 148)
    ....
    DNS server 1.1.1.1 A query attempt 31: failed to look up ntp.eng.oxide.computer: proto error: io error: No route to host (os error 148)
    DNS server 9.9.9.9 A query attempt 1: failed to look up ntp.eng.oxide.computer: proto error: io error: No route to host (os error 148)
    ....
    DNS server 9.9.9.9 A query attempt 31: failed to look up ntp.eng.oxide.computer: proto error: io error: No route to host (os error 148)
* Checking for external NTP connectivity (6.051µs)
    missing metadata
    no NTP IP addresses known (DNS failure?)
✔ Cleaning up host OS routing configuration (56.628µs)
    missing metadata
✘ Cleaning up host OS IP address configuration (20.848173ms)
    missing metadata
    failed to remove uplink SMF property "uplinks/qsfp0_0": command failed (status exit status: 1); stdout="" stderr="svccfg: No such property uplinks/qsfp0_0.\n"
Connection to fe80::aa40:25ff:fe05:2702%london_sw0tp0 closed.

Without addresses and routes, preflight should just stop early and complain.

Start with the preflight uplink entry point and reproduce the supplied configuration where switch 0 has empty addresses and routes. Trace the preflight steps to identify where host IP and routing setup begins; done means an incomplete network configuration stops early with a clear complaint instead of attempting host setup.