When a user has not selected a specific "billing account" or "re-attribution ID" yet, we can set it automatically in the following cases:
- The user joins a team with usage-based billing enabled
- One of the user's teams upgrades to usage-based billing
Similarly, when a user has selected a specific team as "billing account" or "re-attribution ID", we should probably unset this value again when:
- The user leaves, or is removed from, the selected team