fix(geolocate): always use netxlite functionality (#976)

This change ensures that, in turn, we're able to "remote" all the traffic generated by the `geolocate` package, rather than missing some bits of it that were still using the standard library and caused _some_ geolocations to geolocate as the local host rather than as the remote host.

Extracted from https://github.com/ooni/probe-cli/pull/969, where we tested this functionality.

Closes https://github.com/ooni/probe/issues/1383 (which was long overdue).

Part of https://github.com/ooni/probe/issues/2340, because it allows us to make progress with that.

internal/engine/geolocate/geolocate.go

@@ -90,7 +90,9 @@ func NewTask(config Config) *Task {
 		probeIPLookupper:     ipLookupClient(config),
 		probeASNLookupper:    mmdbLookupper{},
 		resolverASNLookupper: mmdbLookupper{},
-		resolverIPLookupper:  resolverLookupClient{},
+		resolverIPLookupper: resolverLookupClient{
+			Resolver: config.Resolver,
+		},
 	}
 }