Auto hide IllustrationPreference when lottie file is empty

Flag: com.android.settingslib.widget.flags.auto_hide_lottie_res
Bug: 337873972
Test: unit test
Test: manual: delete `lottie_adaptive_brightness.json` from overlay, navigate to Display > Adaptive Brightness -- verify no empty container
Change-Id: I873976d3e87b119a3ee690d95c68149f249fe7a9
diff --git a/packages/SettingsLib/tests/robotests/Android.bp b/packages/SettingsLib/tests/robotests/Android.bp
index f4ddd0a..f87b519 100644
--- a/packages/SettingsLib/tests/robotests/Android.bp
+++ b/packages/SettingsLib/tests/robotests/Android.bp
@@ -51,6 +51,7 @@
         "androidx.core_core",
         "flag-junit",
         "settingslib_media_flags_lib",
+        "settingslib_illustrationpreference_flags_lib",
         "testng", // TODO: remove once JUnit on Android provides assertThrows
     ],
     java_resource_dirs: ["config"],