Make the deleteAllKey feature aware of the DSU mode

Currently, the vold detects the factory reset by checking the
metadata encryption key. This logic is only valid when the
device is not in DSU mode.

Bug: 199222795
Test: run DSU installation on a Pixel device
Change-Id: Ib40bd44d2ef7c872eba177c9ccfefac8934a49e6
1 file changed