Merge "Remove legacy activity starter code" into udc-dev am: 2222c55fc2

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/22976334

Change-Id: I1e1d78921650d404bcc0bbb984c361167661b3ad
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>