fix: Fix slow tx processing on some edge cases

Author: msbrogli

hathor/consensus/transaction_consensus.py

@@ -234,6 +234,8 @@ def update_voided_info(self, tx: Transaction) -> None:
         for h in meta.conflict_with or []:
             conflict_tx = cast(Transaction, tx.storage.get_transaction(h))
             conflict_tx_meta = conflict_tx.get_metadata()
+            if conflict_tx_meta.first_block is not None:
+                continue
             if conflict_tx_meta.voided_by:
                 self.mark_as_voided(conflict_tx)