Fade out UFPS icon when launching an app over it (1/2)

Before this CL, the UDFPS affordance would instantly disappear after
launching an Activity (like Device Controls) over the lockscreen.

This CL now nicely fades out the affordance during the launch animation,
unless the Activity requested the UDFPS (like the Wallet).

See b/213555622#comment1 for before/after videos.

Bug: 213555622
Test: Open device controls and wallet over lockscreen
Change-Id: I589a4a6c10a118d05fae87b70d14c924d468b63f