Remove deprecated fields from update_metadata protobuf am: 9ae7dc6045 am: 2d426ae71c am: e737675ba4 am: cf44f5837f am: b84ed0e5b7

Original change: https://android-review.googlesource.com/c/platform/system/update_engine/+/2056748

Change-Id: Icf9b70a2b6ee2c904b3862a30b9c06944135fc45
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>