Replace system_ext container with system

Bug: b/365135457
Test: m
Flag: EXEMPT refactor
Change-Id: I5521307c4b816d9802cb5f676d11c0b89cdfa862
diff --git a/aconfig/launcher_overview.aconfig b/aconfig/launcher_overview.aconfig
index 23733a4..853faf8 100644
--- a/aconfig/launcher_overview.aconfig
+++ b/aconfig/launcher_overview.aconfig
@@ -1,5 +1,5 @@
 package: "com.android.launcher3"
-container: "system_ext"
+container: "system"
 
 flag {
     name: "enable_grid_only_overview"