Admin controlled contact groups for Teams are available via the O365 Global Address List (GAL). Please see documentation here: https://docs.microsoft.com/exchange/address-books/address-lists/create-global-address-list.
The team is looking into this feature and considering solutions. We will update when there is more information to share.
Thank you for your continued feedback. The feature team is currently reviewing this ask and investigating how best to accomplish this. Please continue to provide your comments and votes. We will post an update as soon as one is available.