Take advantage of backgroundFetch (not just background delivery of BG data) to upload CBG data.
This is more useful if we do end up using a local DB cache (Realm) of HealthKit BG data, since we can then upload from our local DB while phone is locked.
That said, at least for Current mode samples, the background uploading improvements are such that shortly after phone is unlocked, we immediately upload latest samples in background. And the foreground manual sync improvements also should work well. So, the need for this might be less now.