Fix delete face button disappear after reenroll

Test: manual test - 1.enroll a face 2. delete the face and reenroll 3.
back to face settings page, the button is delete button instead of set
up button
Bug: 285806446

Change-Id: I6739296b0b099446489956f8f609c87600ffdaa3

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

@@ -237,6 +237,8 @@ public class FaceSettings extends DashboardFragment {
     public void onStart() {
         super.onStart();
         final boolean hasEnrolled = mFaceManager.hasEnrolledTemplates(mUserId);
+        mEnrollButton.setVisible(!hasEnrolled);
+        mRemoveButton.setVisible(hasEnrolled);
 
         // When the user has face id registered but failed enrolling in device lock state,
         // lead users directly to the confirm deletion dialog in Face Unlock settings.