Code review comment for ~darren-birkett/cloud-init:fix-infiniband-1847114

Hi Ryan. I don't mind working on a patch to support ib in netplan, but it seems like that should probably sit in its own separate patch rather than trying to lump it in with this fix specifically for eni?

I can raise a bug for netplan support and self-assign if you agree? In which case, the unittests for this patchset are passing for eni and sysconfig now so it should be good to go.