Fix the blinded v2 flow for local payloads

[pawanjay176]

Issue Addressed

N/A

Proposed Changes

The full to blinded conversion here

lighthouse/beacon_node/execution_layer/src/lib.rs

Lines 175 to 189 in a3fb27c

	impl<T: EthSpec> From<BlockProposalContents<T, FullPayload<T>>>
	for BlockProposalContents<T, BlindedPayload<T>>
	{
	fn from(item: BlockProposalContents<T, FullPayload<T>>) -> Self {
	let block_value = item.block_value().to_owned();
	let blinded_payload: BlockProposalContents<T, BlindedPayload<T>> =
	BlockProposalContents::Payload {
	payload: item.to_payload().execution_payload().into(),
	block_value,
	};
	blinded_payload
	}
	}

was always returning a pre-deneb payload.

This caused the v1/validator/blinded_blocks/ endpoint to fail when returning a block from the local EL as the kzg commitment ended up being None here

lighthouse/beacon_node/beacon_chain/src/beacon_chain.rs

Lines 5168 to 5169 in a3fb27c

	blob_kzg_commitments: kzg_commitments
	.ok_or(BlockProductionError::InvalidPayloadFork)?,