Remove unused AllocationBacking am: 8941e34d37 am: 1675211aa9

Original change: https://android-review.googlesource.com/c/platform/frameworks/base/+/2722393

Change-Id: I8a95dc99dbf66e69f28c4809900451fdf57c59e8
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>