settings_connectivity_flags is used from system_ext app

As a system_ext app is using the flags, the flags must be in the
system_ext container instead of the system container.

Bug: 385213580
Test: "adb shell aflags list" must not be changed.
Flag: EXEMPT refactor
Change-Id: I46123b93909acc1e1b2e84ac4fe7898ed5243fc5
diff --git a/aconfig/Android.bp b/aconfig/Android.bp
index cdc8435..4083b14 100644
--- a/aconfig/Android.bp
+++ b/aconfig/Android.bp
@@ -83,7 +83,7 @@
 aconfig_declarations {
     name: "settings_connectivity_flags",
     package: "com.android.settings.connectivity",
-    container: "system",
+    container: "system_ext",
     srcs: ["connectivity/*.aconfig"],
 }