DO NOT MERGE Fix ImageWallpaper memory regression

Scale bitmap to fit display size leads to memory regression, this cl
removes the sacling logic and also disable wallpaper transitions when
the bitmap size is smaller than display size to avoid broken visual.
We backport the solution to Q.

Bug: 147379974
Bug: 145897588
Bug: 124838911
Test: Manually
Test: atest com.android.systemui
Test: adb shell dumpsys SurfaceFlinger, then check layer size of ImageWallpaper
Merged-In: I243274af54538fc89268c448aa2c5a95f63c7ae3
Change-Id: If348748ec453f2b35b25576181c8a144496e258c