Don't panic if no certificates found am: b7550aa0

Original change: https://android-review.googlesource.com/c/platform/build/soong/+/2596605



Change-Id: Ibd97087589c504285c68b98142927878219bdfb9
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>