trusty: allow disabling of confirmation UI am: 034998f474

Original change: https://android-review.googlesource.com/c/trusty/app/confirmationui/+/2882786

Change-Id: I45449c4abaea7f262ade2e7e064648c09617d344
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>