Run liveSync/localSync.complete() earlier

The complete() function makes some system operations and should not rely
on a callback, potentially sent late by 3P wallpapers, to modify
WallpaperData objects. Race conditions may occurs if two calls to
setWallpaperComponent() are trigerred with a short delay, which can put
the system in an inconsistent state.

Now, the complete() function is called under the lock from
setWallpaperComponent, and all operations on the WallpaperData objects
are done atomically.

Calling complete() before the surface is created and drawn should not
create any issue, since the complete() function only changes fields in
WallpaperManagerService and does not change anything in the engine
itself.

The complete() function is called earlier but in the same cases as
before: it is called as long as bindServiceAsUser succeeds, even if the
wallpaper later crashes in a function like onSurfaceRedrawNeeded. If the
binding succeeds, we always want to call complete() in order to be in a
consistent state. Then a wallpaper crash will trigger a call to
clearWallpaperLocked(); and this method expects WallpaperManagerService
to be in a clean state when it is called.

A new CTS for the wallpaper clear logic, ag/24678388, will be
introduced soon. This test sometimes fails due to race conditions
without this CL; it only works when adding a delay of about 5s between
two consecutive calls to WallpaperManager#clear(). The delay is not
needed with this change.

Moreover this change makes the WallpaperManagerTest much faster; e.g. on
foldable it goes from 3-4s per wallpaper change to about 500ms.

Calls to notifyWallpaperColorsChanged() inside complete() have been
removed: they are for a sys + lock -> lock migration. But in that case,
the lock screen keeps the same wallpaper and the same colors, so this
call is not necessary. One CTS needs to be adapted accordingly.

Flag: lockscreen lwp
Bug: 298366419
Test: atest WallpaperManagerTest
Test: crystalball boot time tests to look for regressions
Change-Id: I8ac3eede864bf11593bd7e70f5ca4e7f5711bc73