configtest: T4382: fix missing delete of 'ipsec-interfaces' node
configtest: T4382: fix missing delete of 'ipsec-interfaces' node

Migration of bgp-azure-ipsec-gateway and bgp_dmvpn_hub reveals that
migration script ipsec/5-to-6 leaves the empty node 'ipsec-interfaces'
after moving the interface; fix the migration script, as it is not yet
in 1.3.

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