Merge "Add a method in vold to unmount app data and obb dir for testing" am: 502c283c22 am: 9ae91a47f9 am: ea35110bde

Original change: https://android-review.googlesource.com/c/platform/system/vold/+/1551802

MUST ONLY BE SUBMITTED BY AUTOMERGER

Change-Id: Ibd5d10109e79f29eb9b6071a2b2734d3a48cea20