Update fp => lock icon transition to NOT be reversible

The transition doesn't support the reverse transition
and would cause the visual state of the icon to be
wrong when attempting to reverse the animation which
could occur on user switch (many subsequent lock/fp/lock/fp
updates).

Bug: 340845797
Test: manually switch users with FP enrolled,
observe fingerprint icon
Flag: EXEMPT bugfix

Change-Id: Ia006209cf11b642b8c7f0b6f0edb2a99110bfcaa