I was thinking that that the "Fixed locked empty drawers to not accept items through sided inventory" change should possibly have a config option, so that there will be a choice between old and new way of drawer behavior

Good for SSP but not servers. I designed the API in a way that I could theoretically introduce another key that enforced the older behavior. I wanted to get some feedback before trying to support that. I don't want the confusion of multiple keys if no one actually depended on that bug.