Unmount public volume if FUSE mount fails am: f71707916f am: 0f9690e391 am: a09ee4ff8f am: 2e4db39ba0

Original change: https://googleplex-android-review.googlesource.com/c/platform/system/vold/+/11900947

Change-Id: I05c85ab4c93813fefee53af316eab441167cde63