IKE lifetime should start from 0 for disabling rekey
https://github.com/vyos/vyos-1x/blob/b65296a0ff39e66d87e916971477cce351f6d5a5/interface-definitions/vpn-ipsec.xml.in#L360-L364
Request from the forum
vyos@r14# set vpn ipsec ike-group IKE lifetime Possible completions: <30-86400> IKE lifetime in seconds