Some Libp2p metrics are listed but no values returned

[jakubgs]

Those metrics seem broken, they are listed, just return nothing:

 > curl -s 0:9100/metrics | grep libp2p_peers_identity
# HELP libp2p_peers_identity peers identities
# TYPE libp2p_peers_identity gauge

 > curl -s 0:9100/metrics | grep libp2p_peers_traffic_write
# HELP libp2p_peers_traffic_write outgoing traffic
# TYPE libp2p_peers_traffic_write counter

 > curl -s 0:9100/metrics | grep libp2p_peers_traffic_read
# HELP libp2p_peers_traffic_read incoming traffic
# TYPE libp2p_peers_traffic_read counter

And they feature prominenty in Nimbus dashboards:

Started happening since 25.10.0 release of nimbus-eth2.