Make DeviceConfig's storage nam space _native_boot

Replace all uses of DeviceConfig#NAMESPACE_STORAGE with
DeviceConfig#NAMESPACE_STORAGE_NATIVE_BOOT.
Keep DeviceConfig#NAMESPACE_STORAGE (to keep api checks happy) and mark
it as @Deprecated.

Test: build and flash - device successfully boots
Bug: 140803239
Change-Id: I9b1f0d1fd1996fe12cad67374d9a321c272e1da5