Spent is spent. In other words you've already done your time. If you mention it on your application I doubt you will proceed any further.
I wouldn't mention it and if it ever came up (which I highly doubt) then deal with it then. If they've spent thousands on training you and you've been a good honest worker for the previous so many years I doubt they'll sack you over a minor altercation with the law over 10 years earlier!
Only my two cents worth!
