installd: Run dex2oat with relative path to the APK

Previous CL (I6aaddffe79c55b9a6560c2d6542cf87abbd4fb11) started
passing the absolute path of an APK to dex2oat. This renders APKs
dexopted while in a temporary folder during install out-of-date when
moved to the final location.

Bug: 26409579
Change-Id: Icccf2d1bb34e2d5f4d98efae3c8f5609784abafd