Position fingerprint progress in the center on landscape

Update the layout of the landscape fingerprint enrolling screen to
be consistent with fingerprint find sensor, which vertically centers
the graphic on the right.
Also added back the accessibility live region for TalkBack.

Bug: 30288351
Bug: 30287231
Change-Id: Ia5b429215e36bbc108585aa8b14330b77ddc8584
(cherry picked from commit c8157513)