Set the container field of aconfig flags

Please see go/aconfig-flag-containers for more context

Test: m
Bug: 312769710
Change-Id: I828a1a1c5ab944283341ace924db97c4eadb7a7f
diff --git a/aconfig/settings_bluetooth_declarations.aconfig b/aconfig/settings_bluetooth_declarations.aconfig
index 58ddd25..3e771cd 100644
--- a/aconfig/settings_bluetooth_declarations.aconfig
+++ b/aconfig/settings_bluetooth_declarations.aconfig
@@ -1,4 +1,5 @@
 package: "com.android.settings.flags"
+container: "system"
 
 flag {
   name: "enable_offload_bluetooth_operations_to_background_thread"