DB: remove unused global table_prefix
DB: remove unused global table_prefix

I can't find any other reference to $dsn['table_prefix'] or how to define that. I guess this is something obsolete.
samratcis/atk4,xepan/atk4,atk4/atk4,atk4/atk4,xepan/atk4,samratcis/atk4,svisystem/atk4,svisystem/atk4,atk4/atk4,xepan/atk4,atk4/atk4,svisystem/atk4,samratcis/atk4