Fix StorageHostTest#testVerifyStatsExternalConsistent.

This test calculates the size of external storage by walking the
filesystem, and consequently compares that with the reported quota.
Since scoped storage, walking Android/ is no longer allowed, regardless
of the targetSdk. Therefore, manually compute the app data + cache usage
and include it in the total.

Bug: 146419093
Test: atest StorageHostTest#testVerifyStatsExternalConsistent
Change-Id: If7b86374daf8c3aab49fb50704312acd43195b48
(cherry picked from commit bb6d0fe3d5c1d4b929b8c5e64a9539355b6a0b38)
Merged-In: If7b86374daf8c3aab49fb50704312acd43195b48
2 files changed