Avoid unlinking app image file

Avoid erasing the image file in installd in case we abort compilation
due to no new profile data. This prevents the application image file
being turned into a 0 byte file in this case.

The ART image writer erases the file before writing.

Bug: 22858531
Change-Id: I0b35905698662cef80eecfc350e5504bf62a5ac1