fix: always handle payload building for opstack

[mattsse]

this ports missing check for opstack because there we always need to trigger a new payload job if this happens

reth/crates/consensus/beacon/src/engine/mod.rs

Lines 463 to 474 in 9cf8282

	// On Optimism, the proposers are allowed to reorg their own chain at will.
	#[cfg(feature = "optimism")]
	if reth_chainspec::EthChainSpec::chain(self.blockchain.chain_spec().as_ref()).is_optimism()
	{
	debug!(
	target: "consensus::engine",
	fcu_head_num=?header.number,
	current_head_num=?head.number,
	"[Optimism] Allowing beacon reorg to old head"
	);
	return true
	}

This adds is_optimism to ethchainspec trait for simplicity, which isn't great but also not horrible