Set aconfig container to "system"

Bug: 312769710
Flag: NA
Test: TH
Change-Id: I7fbb8e31629b7aa90fbdf2b029932c111cce8d42
diff --git a/aconfig/launcher.aconfig b/aconfig/launcher.aconfig
index a62f809..c8880e9 100644
--- a/aconfig/launcher.aconfig
+++ b/aconfig/launcher.aconfig
@@ -1,4 +1,5 @@
 package: "com.android.launcher3"
+container: "system"
 
 flag {
     name: "enable_expanding_pause_work_button"