Merge "cargo_embargo: include testdata path when File::open fails" into main am: 4f85b5c3fb

Original change: https://android-review.googlesource.com/c/platform/development/+/2798391

Change-Id: I7f50c607e868317fb4f45a0ad4b76927c04914f7
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>