When a topic belongs to category that is read restricted but permission
has not been granted to any groups, publishing ceratin topic tracking state
updates for the topic will result in the `MessageBus::InvalidMessageTarget` error being raised
because we're passing `nil` to `group_ids` which is not support by
MessageBus.
This commit ensures that for said category above, we will publish the
updates to the admin groups.
0403cda1d1