Use accessibilityLiveRegion for ConfirmLockPassword/Pattern errorText

- Revert previous "Add announceForAccessibility to ConfirmLockPattern";
- Add android:accessibilityLiveRegion="polite" for errorText in
  ConfirmLockPassword/Pattern;

Bug:20282779
Change-Id: I4b9c0d461d0dd0504bd88a8a2144e09a42d5f64e

src/com/android/settings/ConfirmLockPassword.java

@@ -377,7 +377,6 @@ public class ConfirmLockPassword extends ConfirmDeviceCredentialBaseActivity {
 
         private void showError(CharSequence msg, long timeout) {
             mErrorTextView.setText(msg);
-            mErrorTextView.announceForAccessibility(mErrorTextView.getText());
             mPasswordEntry.setText(null);
             mHandler.removeCallbacks(mResetErrorRunnable);
             if (timeout != 0) {