The previous implementation would attempt to fetch groups using the end-user's Google auth token. This only worked for admin accounts, or users with 'delegated' access to the `admin.directory.group.readonly` API.
This commit changes the approach to use a single 'service account' for fetching the groups. This removes the need to add permissions to all regular user accounts. I'll be updating the [meta docs](https://meta.discourse.org/t/226850) with instructions on setting up the service account.
This is technically a breaking change in behavior, but the existing implementation was marked experimental, and is currently unusable in production google workspace environments.
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