Fix: Ensure Isthmus withdrawals root validation for non-canonical parent state in Optimism engine

[petrokamin10]

Previously, when state_by_block_hash failed, the validator returned Ok(()), effectively skipping withdrawals root verification for blocks whose parent was not yet in the canonical chain.
This created a window where blocks could bypass a critical consensus check during reorgs or while processing non-canonical branches.

• Fix OpEngineValidator::validate_block_post_execution_with_hashed_state to always validate the Isthmus withdrawals root, even when the parent block state is not yet canonical.
• Resolve state lookups by first trying historical state and then pending state; if neither is available, return a consensus error instead of silently accepting the block.