Add missing `packages.cleanup.success` (#28129)

Used at
a3348bfc4d/routers/web/admin/packages.go (L111)

<img width="1325" alt="image"
src="https://github.com/go-gitea/gitea/assets/9418365/60edc1fa-eea8-4d74-a7ec-96bd5461a53f">

options/locale/locale_en-US.ini

@@ -2883,6 +2883,7 @@ packages.package_manage_panel = Package Management
 packages.total_size = Total Size: %s
 packages.unreferenced_size = Unreferenced Size: %s
 packages.cleanup = Clean up expired data
+packages.cleanup.success = Clean up expired data successfully
 packages.owner = Owner
 packages.creator = Creator
 packages.name = Name