Such written or verbal promises don't mean much. The fact is that you disappeared from Qatar without clearing your loan. Now you have job in another country and you have awakened to your loan that is pending payment.
As for your query, it would be difficult for people at QL to answer. I know that at Dubai airport baggage get scanned for illegal items, Whether you will get caught at Dubai airport or allowed to pass through easily, is anyone's guess. I believe only some one in the authority can advise.