Fix resetting of wallpaper offset.

In the initial implementation I had hoped to eliminate
this call to set position, and when I had to add it back
I forgot to restore the wallpaper offseting. Anyway, setWallpaperOffset
sets this position and we need to make sure its not fighting with
setSurfaceBoundaries.

Bug: 74500386
Test: Manual. go/wm-smoke
Change-Id: Iac5d157090ea512acbe4892d57eee6e1e423f18d