Creates enp1s0.50 on nik-debian (no L3 address, VLAN 40/node IP/default
route untouched) for Multus to later attach macvlan/ipvlan workloads to.
Verified live: enp1s0.50 is up with no IPv4 address (only the automatic
IPv6 link-local, which is expected and harmless), default route
unchanged.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
