engine: return -38003 for FCUv2 payloadAttributes mismatch

[Muzry]

This PR updates engine_forkchoiceUpdatedV2 to return -38003: Invalid payload attributes when the wrong payloadAttributes version is used.

In particular, FCUv2 payload-attribute version mismatches such as:

• missing withdrawals at or after Shanghai
• unexpected withdrawals before Shanghai

should be treated as Invalid payload attributes, not Invalid params.

Why

This change aligns the client with the latest Engine API spec update in:

• engine: use -38003 for wrong payloadAttributes version in forkchoiceUpdatedV2 ethereum/execution-apis#761

It also follows the implementation discussion and prior client-side change in:

• eth/catalyst: return -32602 for FCU V2 wrong payloadAttributes version ethereum/go-ethereum#33918

The spec was clarified so that FCUv2 now behaves consistently with newer forkchoiceUpdated versions for payloadAttributes structure/version
mismatches.

What changed

• Updated FCUv2 payload attributes validation to return -38003 for payloadAttributes version mismatches.
• Added/updated regression coverage for the affected FCUv2 cases.

Hive impact

This fixes the Hive engine-withdrawals failure caused by returning the wrong error code for FCUv2 payloadAttributes mismatches.

Relevant Hive failure:

• https://hive.ethpandaops.io/#/test/generic/1773130719-e0853d5fae804ded99a295a416e78bad

After this change, the client returns the expected error code for the affected FCUv2 cases.

If my understanding or interpretation of the spec change is incorrect, please let me know and I can adjust the implementation accordingly.

[LukaszRozmej]

closing in favor of #10786