Depend on the staging dir files from soong-built image

The soong-built image will no longer copy its files to the staging
dir itself, those files will now be copied by an android_device
module in soong-only builds. However, for soong+make builds, we
need the copy to still happen, so do it in make.

Bug: 376727180
Test: m
Change-Id: I765d6afa6dad17cf34f37647caaf6fcc63f3ae9a