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

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



Change-Id: I405d8bbbde142073214adbf663813f25667835fa
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>