Unfortunately this checkbox will not be implemented anymore.
There was a request to do it here
https://github.com/bitcoin/bitcoin/issues/12520The solution was to remove the "New" Button in the address book so it's only possible to create new addresses via the "Receive" tab.
This is the pull request which is already merged into the bitcoin master branch.
https://github.com/bitcoin/bitcoin/pull/12721So with the next bitcoin core release there is no more "New" Button in the address book.
I already implemented this checkbox as I also missed it, but before I got the chance to create a pull request, the "New" Button was removed so my changes are useless now.