log upgrades + prevent dialing of disconnecting peers (#3148)

## Issue Addressed
We still ping peers that are considered in a disconnecting state

## Proposed Changes

Do not ping peers once we decide they are disconnecting
Upgrade logs about ignored rpc messages

## Additional Info
--

beacon_node/lighthouse_network/src/behaviour/mod.rs

@@ -991,7 +991,7 @@ where
             debug!(
                 self.log,
                 "Ignoring rpc message of disconnecting peer";
-                "peer" => %peer_id
+                event
             );
             return;
         }