Enable self-testing by default in rkp factory tool am: ed854b2b3b

Original change: https://googleplex-android-review.googlesource.com/c/platform/system/security/+/23501328

Change-Id: Ia699f38f4a7e28508b7ac6f2133b320d0757d214
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>