Merge "Turn off Back affordance flag" into tm-qpr-dev am: 435bae41

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/19262527



Change-Id: I9d194f7746476b3a509ab489b76c84aac6b7afb4
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>