Finish animation callback set latest value (reland)

Instead of the state on which the animation was started, a cancelled
animation will set the latest state. This ensures that we don't
accidentally end up in an old state if the animation callback is
executed slighly after the next dim state update.

Bug: 357028844
Test: DimmerTests
Flag: EXEMPT change is minor
Change-Id: I292a72dbf2e6d9b83db6d989714a8faad4367d05