For me only SystemUpdateService$SecretCodeReceiver had to be disabled. All other activities, receivers and services with a name starting with "SystemUpdate" were already disabled. I used ADB + "pm disable" to disable this one component.
Here is a list of commands to disable all SystemUpdate "stuff" via ADB (of course it requires a rooted phone with some sort of "su" installed):
main.dbdatabase (which is inside your