fix container designation, it should be system_ext

Bug: b/338095619
Change-Id: I8ee2fd5fad529da2026af77f969abbf88e636ac3
diff --git a/aconfig/Android.bp b/aconfig/Android.bp
index d511d04..f7b4881 100644
--- a/aconfig/Android.bp
+++ b/aconfig/Android.bp
@@ -6,7 +6,7 @@
 aconfig_declarations {
     name: "aconfig_settings_flags",
     package: "com.android.settings.flags",
-    container: "system",
+    container: "system_ext",
     srcs: [
         "*.aconfig",
     ],