server: Treat non-default route as host route

When constructing ip route command in addRouteWithMetric,
we used to check whether the given route is a host route.
In some cases, the isHostRoute() check can return false for
non-default routes. To make this check more foolproof,
check whether a route is non-default in order to treat it
as a host route.

Change-Id: I5e396e67e1c82bbe22600c47f1e52cc7c750cdc6