cargo_embargo: detect and ignore harness-less tests

These currently cause cargo_embargo to fail. We should support them
eventually, but for now we'll ignore them to unblock crosvm merges.

Test: external/crosvm/android-merge-2-cargo-embargo.sh
Bug: 275386231
Change-Id: I3e156afa5672ddd6257c7caabd05346e060448fb
2 files changed