bug(l1): connection attempt on already connected peer due to revalidation

[fmoletta]

During peer revalidation we ping the least recently pinged peers and expect them to reply with a pong message. When a peer replies with pong we also try to initiate a connection with it. If a peer we are already connected to were to fall under this revalidation then we would attempt to initiate a second connection with the peer to which the peer would reply to by disconnecting from us.
Here are some logs to illustrate the problem:

025-01-09T19:24:05.888572Z  INFO ethrex_net::kademlia: Snap Peers: 2 / Active Peers 2 / Total Peers: 101
2025-01-09T19:24:05.888674Z  INFO ethrex_net::kademlia: Active Peers ID: 0xa343…5072, 0xac90…5e2b
2025-01-09T19:24:05.888748Z  INFO ethrex_net::sync: Requesting Block Headers from 0xde8f…79e7
2025-01-09T19:24:05.889382Z  INFO ethrex_net: Running peer revalidation
2025-01-09T19:24:05.891256Z  INFO ethrex_net: Pinging peer 0xa343…5072 to re-validate!
2025-01-09T19:24:05.892743Z  INFO ethrex_net: Pinging peer 0x0010…e3e7 to re-validate!
2025-01-09T19:24:05.894219Z  INFO ethrex_net: Pinging peer 0x743d…7122 to re-validate!
2025-01-09T19:24:05.894262Z  INFO ethrex_net: Peer revalidation finished
2025-01-09T19:24:05.926046Z  INFO ethrex_net: Peer 0xa343…5072 answered ping with pong
2025-01-09T19:24:05.929520Z  INFO ethrex_net: Peer 0x743d…7122 answered ping with pong
2025-01-09T19:24:05.958563Z  INFO ethrex_net: Starting Peer as Initiator
2025-01-09T19:24:05.970228Z  INFO ethrex_net: Starting Peer as Initiator
2025-01-09T19:24:06.006510Z ERROR ethrex_net::rlpx::connection: Handshake failed: (Peer disconnected due to: Already connected), discarding peer 0xa343…5072

We should read the spec in order to handle this case accordingly