Delete NPVC.mIsLaunchTransitionFinished and associated dead code

NPVC.mIsLaunchTransitionFinished is only ever set to false, so it
can be deleted along with any code gated by a true value. Also,
KeyguardViewController.shouldDisableWindowAnimationsForUnlock has
only one impl which passes on the value, so it and all code that
needs it to return true can be deleted as well.

Fixes: 256593504
Test: atest and manual
Change-Id: I696be4b8328b14ec7588f9d90d3fd6a4c8d85138