Merge from Widevine repo of http://go/wvgerrit/142150 (part 2)
For an EVT device, without a keybox or with a test keybox, we want it
to fall back to L3. However, when running the unit or integration
tests it should continue running tests with test keybox. This will
allow us to test L1 oemcrypto on an EVT device, while still using an
EVT device for dogfooding video content at the L3 level.
Bug: 210807585
Bug: 210823889
Change-Id: I30c35134239db35bb39f11f75220063181987763