Gloas modified p2p topics

[shane-moore]

Modified p2p topics for gloas:

beacon_block

• all validations regarding ExecutionPayload in the BeaconBlockBody were removed for gloas
  • Note that there are new validations required to ensure that the signed_execution_payload_bid.message.parent_block_hash has passed a validation check. My thoughts on how to accomplish this are documented in the diffs and will likely be accomplished as part of the envelope_verification.rs initiative
• beacon_aggregate_and_proof global topic verification modified with attestation.data.index validations per spec
• beacon_attestation_{subnet_id} global topic verification modified with attestation.data.index validations per spec

[shane-moore]

Closing — fully upstreamed.

Both changes in this PR are now in upstream/unstable:

• Attestation data.index validation for GLOAS: landed via Gloas attestation verification  sigp/lighthouse#8705 ("Gloas attestation verification", 68ad9758a) and Gloas set AttestationData.index  sigp/lighthouse#9100 ("Gloas set AttestationData.index", 276c4d5ff). Upstream attestation_verification.rs:890-924 has the same fork_name.gloas_enabled() branching and the index >= 2 check, applied to both unaggregated and aggregated paths. Upstream uses CommitteeIndexInvalid rather than the PR's CommitteeIndexTooHigh.

• Bid parent_block_root == block.parent_root: landed via Implement gloas block gossip verification changes sigp/lighthouse#8878 ("Implement gloas block gossip verification changes", dcc43e3d2). Upstream block_verification.rs:890-897 has the same guard, returning BlockError::BidParentRootMismatch.