Add a config for the face enroll introduction activity

Test: manual

Bug: 185426108
Change-Id: I42e1f8dd5a20e8066fbd1374283acc1228427d45

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

@@ -68,7 +68,7 @@ public class FaceStatusPreferenceController extends BiometricStatusPreferenceCon
 
     @Override
     protected String getEnrollClassName() {
-        return FaceEnrollIntroduction.class.getName();
+        return mContext.getResources().getString(R.string.config_face_enroll_introduction);
     }
 
 }