Thank you for your patience, I’ve contacted the Product team and searched for a solution to your issue. Terraform doesn’t mention this option in google apps social connection settings, but based on Docs from here and fetching social connection details with Management API, the name of the setting you are looking for is "map_user_id_to_id": true
By appending your existing Terraform new social configuration with this line of code, you should be able to change this setting.
Let me know if this works.
Thanks
Dawid