Factory reset: Wipe media by default

These hidden APIs are called from some public APIs (DevicePolicyManager),
so we shouldn't change the default behavior.

The intent API should also be considered public, so change that as well.

FEIJ-1610
Change-Id: Ib9591c122dbe6168e7e237444c754b9608be0953
(cherry picked from commit 75c84499)