This fixes the following race in reconfiguring link:
1. an interface requests UUID.
2. the interface is reconfigured and link_configure() is called.
3. sd-lldp client is started on the interface (it is enabled by default).
4. networkd acquires UUID, and get_product_uuid_handler() calls
link_configure() for the link again.
5. link_lldp_rx_configure() fails to set ifindex for already running
sd-lldp client.
6. the link enters failed state.
link_free_carrier_maps(link);
link_free_engines(link);
link->network = network_unref(link->network);
+ link_unref(set_remove(link->manager->links_requesting_uuid, link));
/* Then, apply new .network file */
r = network_apply(network, link);