Adding error for when overlayfs is enabled in OTA am: eede4c8305

Original change: https://android-review.googlesource.com/c/platform/system/update_engine/+/2624718

Change-Id: I8735aac3089efbffd0d04918ee1f8c0bb930d600
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>