DoS protection for invalid proof gossip in EIP-8025

[frisitano]

Overview

PR #5055 originally included two coupled mechanisms intended to mitigate denial-of-service via invalid execution proof gossip:

1. A gossipsub [IGNORE] rule that blacklisted any validator after they sent a single invalid proof.
2. An honest-validator behaviour (Proof re-signing) allowing a validator to re-sign and re-broadcast a proof originally signed by a blacklisted validator, ensuring proof availability for peers that had discarded the original.

Both were removed from #5055 per discussion with @jihoonsong, pending a deeper evaluation of attack feasibility and the sufficiency of existing libp2p scoring.

Reference

Writeup of the open questions and proposed approaches: https://hackmd.io/@frisitano/HkCzVt-a-x

[jihoonsong]

FYI, here is the link to our discussion for better visibility.