refactor flavor db fakes in prep for object-ify flavors

This change is to help split up the patches for object-ifying flavors.
It refactors db fakes to provide default values for fields that are
not nullable in flavor objects.

Change-Id: I18575703cd5c52d4f446c9bca1edd7baf33b416f
Merge "refactor flavor db fakes in prep for object-ify flavors"