certify_bootimg: makes gki-info.txt optional am: 79627361ad am: 6236378e71 am: 8b855eb5f8 am: cade007f98 am: 4b5ad16a3a am: 2fe7d1583e

Original change: https://android-review.googlesource.com/c/platform/system/tools/mkbootimg/+/2051402

Change-Id: I76938a9b97bcff2752e9405275ec8bef52fb1c57
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>