Merge "DSUService: Deduplicate InstallUserdata() and InstallScratch()" am: c2c3a3c7d4 am: 5f2f17fc4a

Original change: https://android-review.googlesource.com/c/platform/frameworks/base/+/1662402

Change-Id: I08e9707a2a6ecf8b82c12595335aa22adc4ec165