update_engine: use error_code for std::filesystem am: a77e645f14 am: a88ba553e5

Original change: https://android-review.googlesource.com/c/platform/system/update_engine/+/3217657

Change-Id: Ib0d46efddf40a0724498a344e159412494c492e2
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>