Wait for systemui udfps overlay ready to show settings udfps enroll view. am:...

Wait for systemui udfps overlay ready to show settings udfps enroll view. am: be823bc5 am: 93bcf812 am: ed83c055

Original change: https://googleplex-android-review.googlesource.com/c/platform/packages/apps/Settings/+/23814463



Change-Id: I93fe1f323682b2239bcf304a98a4018b16f53b3b
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>