Revert "Replace UDFPS lockscreen a11y announcements with live region"

This reverts commit 868f3d76.

Reason for revert: reverting to original accessibility state with announcements
(cherry picked from https://googleplex-android-review.googlesource.com/q/commit:28c239fd5be8202fc9aa286abef43629a6d3917f)
Merged-In: I5b7cf536cf0277a88e89f71f95bdd6d454c69a57
Change-Id: I5b7cf536cf0277a88e89f71f95bdd6d454c69a57