SaaS golden data (routes-ea* captures) proves that approved exit
routes appear in every peer's AllowedIPs. The previous commit
incorrectly dropped them based on a via-grant scenario where
exit routes were not approved.
TestRoutesCompatPeerAllowedIPs validates this against all captured
netmaps: peer AllowedIPs = node IPs + HA primary routes + exit
routes, filtered through ReduceRoutes.
Updates #3157
Kristoffer Dalby
fa94bd949c