Merge "Wait for disconnect when rebooting to userspace FB" into main am: 73c6f08f

Original change: https://android-review.googlesource.com/c/platform/system/core/+/3009736



Change-Id: I35b1cc4d24244efe4f38abb4036a698c142f128f
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>