Adjust obb path to be able calculate external's codeSize well wo/quota

Without quota, installd doesn't not calculate codeSize correctly
use Android/obb, So we adjust to Android/obb.
And we needed to remove external's codeSize from dataSize.

- Test: run cts -m CtsAppSecurityHostTestCases
        -t android.appsecurity.cts.StorageHostTest#testVerifyStats

Change-Id: I253c62ef4a9171242e10c0bcf57047c207278868