[Cherry-pick] Add warning on enabling ANGLE. am: d3c75bd9eb

Original change: https://android-review.googlesource.com/c/platform/packages/apps/Settings/+/2794036

Change-Id: I8a93c58cf80f113277fc269e42c02e52e9d702c2
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>