Propagate the merge failure code to SnapshotMergeStats. am: 6ac3d47472 am: 4f94f1c101

Original change: https://android-review.googlesource.com/c/platform/system/update_engine/+/1675999

Change-Id: Id8640f0e4b966f52e5c84816a49d3e1c4be56322
diff --git a/aosp/cleanup_previous_update_action.cc b/aosp/cleanup_previous_update_action.cc
index 68954f6..a902eaf 100644
--- a/aosp/cleanup_previous_update_action.cc
+++ b/aosp/cleanup_previous_update_action.cc
@@ -324,6 +324,7 @@
 
     case UpdateState::MergeFailed: {
       LOG(ERROR) << "Merge failed. Device may be corrupted.";
+      merge_stats_->set_merge_failure_code(snapshot_->ReadMergeFailureCode());
       processor_->ActionComplete(this, ErrorCode::kDeviceCorrupted);
       return;
     }