Specifying "Global Static Routes" causes cloud-init to fail to parse instance metadata

/kind bug

What steps did you take and what happened: I tried to specify "global static routes" in a clusterclass as this field was available:

https://github.com/kubernetes-sigs/cluster-api-provider-vsphere/blob/a2f8e744a7f4f72cdd5c1d33256cae49b3aa9021/apis/v1beta1/types.go#L271-L274

Upon inspecting instance-data.json, it appears the following instance metadata template was rendered correctly:

https://github.com/kubernetes-sigs/cluster-api-provider-vsphere/blob/a2f8e744a7f4f72cdd5c1d33256cae49b3aa9021/pkg/util/constants.go#L141-L148

"network": {
   "config": {
       "ethernets": {
           "id0": {
               "addresses": [
                   "192.168.117.162/24"
               ],
               "gateway4": "192.168.117.1",
               "match": {
                   "macaddress": "00:50:56:81:da:4e"
               },
               "nameservers": {
                   "addresses": [
                       "192.168.117.1"
                   ]
               },
               "set-name": "eth0",
               "wakeonlan": true
           }
       },
       "routes": [
           {
               "metric": 222,
               "to": "8.8.8.8",
               "via": "192.168.117.1"
           }
       ],
       "version": 2
   }

But running journalctl reveals that cloud-init threw an exception upon finding "routes" in the network config.

Aug 04 23:32:34 berry-lg59h-z4nbt cloud-init[444]: [CLOUDINIT]2023-08-04 23:32:34,696 - util.py[DEBUG]: failed stage init-local
                                                   Traceback (most recent call last):
                                                     File "/usr/lib/python3.7/site-packages/cloudinit/net/network_state.py", line 355, in parse_config_v2
                                                       handler = self.command_handlers[command_type]
                                                   KeyError: 'routes'

                                                   The above exception was the direct cause of the following exception:

                                                   Traceback (most recent call last):
                                                     File "/usr/lib/python3.7/site-packages/cloudinit/cmd/main.py", line 767, in status_wrapper
                                                       ret = functor(name, args)
                                                     File "/usr/lib/python3.7/site-packages/cloudinit/cmd/main.py", line 433, in main_init
                                                       init.apply_network_config(bring_up=bring_up_interfaces)
                                                     File "/usr/lib/python3.7/site-packages/cloudinit/stages.py", line 943, in apply_network_config
                                                       netcfg, bring_up=bring_up
                                                     File "/usr/lib/python3.7/site-packages/cloudinit/distros/__init__.py", line 268, in apply_network_config
                                                       network_state = parse_net_config_data(netconfig, renderer=renderer)
                                                     File "/usr/lib/python3.7/site-packages/cloudinit/net/network_state.py", line 1103, in parse_net_config_data
                                                       nsi.parse_config(skip_broken=skip_broken)
                                                     File "/usr/lib/python3.7/site-packages/cloudinit/net/network_state.py", line 306, in parse_config
                                                       self.parse_config_v2(skip_broken=skip_broken)
                                                     File "/usr/lib/python3.7/site-packages/cloudinit/net/network_state.py", line 359, in parse_config_v2
                                                       ) from e
                                                   RuntimeError: No handler found for command 'routes'

After reading https://cloudinit.readthedocs.io/en/latest/reference/network-config-format-v2.html#network-config-v2, it does not appear that "routes" was a valid key under "network".

Specifying "routes" per-device works as expected, however.

What did you expect to happen: Specifying global static routes should either be not supported or translated to a per-device setting somehow.

Anything else you would like to add:

I also tried this with Ubuntu, but the machine did not acquire an IP address so I was unable to SSH in to see the problem. I suspect that the network config was invalid and so it was unable to acquire the static IP set in the instance metadata.

Environment:

• Cluster-api-provider-vsphere version: v1.7.0
• Kubernetes version: (use kubectl version): v1.26.5
• OS (e.g. from /etc/os-release): Photon OS 3.0