[RESTRICT AUTOMERGE] StorageManagerService: don't ignore failures to prepare user storage am: f80dd3ecd4

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/17416378

Change-Id: If7e2bb688e37a55b874d25f4e1621f3998b4d9af
Ignore-AOSP-First: this is an automerge
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>