Remove plain `startActivity` plumbing APIs am: 031a84bc72 am: b9fb4295e3

Original change: https://googleplex-android-review.googlesource.com/c/platform/packages/modules/IntentResolver/+/21353731

Change-Id: Ia64a1acd19b5d5246116cbcf08839bdfd812172f
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>