migrator: ospf: T3267: cleanup empty interface "ip" nodes
migrator: ospf: T3267: cleanup empty interface "ip" nodes

When per interface OSPF configuration is migrated into "protocols ospf interface"
we should cleanup and empty ip {} node unter the individual interface. This
makes the config look more nicely.

vyos/vyos-1x,vyos/vyos-1x,vyos/vyos-1x,vyos/vyos-1x