Ignore wallpaper enter animation

The alpha animation is almost unnoticeable and rare to
execute (e.g. orientation change across visibility change).
It would be more efficient, consistent and less error
prone to skip the animation which user won't aware it.

Though the original issue is about the surface position
of wallpaper animation leash:
1. WallpaperController#updateWallpaperOffset may calculate
   wrong offset by using frames in different rotation.
   This can be fixed by early return if !isVisible().
2. Even if the wallpaper offset is correct, the surface
   position calculated by wallpaper scale will be ignored
   in WindowState#updateSurfacePosition because the window
   is animating (mSurfaceAnimator.hasLeash()).
   This can be fixed by relaxing the condition if wallpaper
   scale is not 1.
But as the reason described above, the simple bypass has more
benefit.

Bug: 191441606
Test: Launch landscape app from portriat home with traditional
      rotation animation (e.g. when IME is vieible), and then
      return to home with fixed (seamless) rotation. The wallpaper
      should not have extra offset temporarily.
Change-Id: Iaa76ea38c27dffb96b2c1d39a3a7a9cd8fe246c4