Hide background when identity check auth is requested

Flag: android.hardware.biometrics.flags.mandatory_biometrics
Fixes: 354014097
Test: atest UtilsTest
Change-Id: I3af06fd9dca2bdc306496f1db832e1d1e2bfe8d2

src/com/android/settings/biometrics/face/FaceSettings.java

@@ -293,7 +293,7 @@ public class FaceSettings extends DashboardFragment {
                 mUserId)) {
             mBiometricsAuthenticationRequested = true;
             Utils.launchBiometricPromptForMandatoryBiometrics(this, BIOMETRIC_AUTH_REQUEST,
-                    mUserId);
+                    mUserId, true /* hideBackground */);
         } else {
             mAttentionController.setToken(mToken);
             mEnrollController.setToken(mToken);