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

aconfig/Android.bp

@@ -83,7 +83,7 @@ java_aconfig_library {
 aconfig_declarations {
     name: "settings_connectivity_flags",
     package: "com.android.settings.connectivity",
-    container: "system",
+    container: "system_ext",
     srcs: ["connectivity/*.aconfig"],
 }
 

aconfig/connectivity/settings_ethernet_declarations.aconfig

@@ -1,5 +1,5 @@
 package: "com.android.settings.connectivity"
-container: "system"
+container: "system_ext"
 
 flag {
   name: "ethernet_settings"