Revert "Replace UDFPS BiometricPrompt a11y announcements with live region"

This reverts commit f022b03c.

Reason for revert: reverting to original accessibility state with announcements
(cherry picked from https://googleplex-android-review.googlesource.com/q/commit:43a88d99f359d6a1760272e91d528f7a48a2dd3b)
Merged-In: Ie835fa8a190603b5f3183ce030514b09ac25de3c
Change-Id: Ie835fa8a190603b5f3183ce030514b09ac25de3c