refactor flavor manage tests in prep for object-ify flavors

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

Change-Id: I59f0254269379ace2186ed90810c5d1a9f09fed7
Merge "refactor flavor manage tests in prep for object-ify flavors"