Remove flicker when unlocking + turning off screen

As soon as the screen starts turning off, powerManager.isInteractive()
becomes false. This forces the home wallpaper leash back to completely
invisible again, which creates a noticeable flicker.

Since the wallpaper is controlled through a leash, we don't have a
problem leaving it at some intermediate opacity. It will get cleaned
up and removed later.

Test: manual (unlock, power off during unlock animation)
Change-Id: I8e8cf659b1f72dd183825f3f0d27c12ddf3c59b2

packages/SystemUI/src/com/android/systemui/keyguard/KeyguardUnlockAnimationController.kt

@@ -902,10 +902,7 @@ class KeyguardUnlockAnimationController @Inject constructor(
     }
 
     fun setWallpaperAppearAmount(amount: Float) {
-        val animationAlpha = when {
-            !powerManager.isInteractive -> 0f
-            else -> amount
-        }
+        val animationAlpha = amount
 
         wallpaperTargets?.forEach { wallpaper ->
             // SyncRtSurfaceTransactionApplier cannot apply transaction when the target view is

packages/SystemUI/tests/src/com/android/systemui/keyguard/KeyguardUnlockAnimationControllerTest.kt

@@ -343,8 +343,6 @@ class KeyguardUnlockAnimationControllerTest : SysuiTestCase() {
         // We expect that we've set the surface behind to alpha = 0f since we're not interactive.
         assertEquals(0f, params.alpha)
         assertTrue(params.matrix.isIdentity)
-        assertEquals("Wallpaper surface was expected to have opacity 0",
-                0f, captorWp.getLastValue().alpha)
 
         verifyNoMoreInteractions(surfaceTransactionApplier)
     }