[automerger skipped] Revert "Expose `FaceManager` APIs as `@SystemApi`." am: 901b3363 -s ours

am skip reason: Merged-In I7e329f311b3eb599195f415cf39dc28bb11139a1 with SHA-1 5fe554bf is already in history

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/26483145



Change-Id: I0fe44f7b195b1a05fd29b002883ee9a9ffa1421d
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>