Downloads updates automatically when Automatic Updates is disabled

### What Happened?

I have Automatic Updates disabled and perform them manually, because I don't like having to reboot to install them.

Yet, it's still downloading updates automatically, and even prompting to install them in the "Shut Down..." dialog (with checkbox ticked by default).

### Steps to Reproduce

1. Disable _Automatic Updates_ in _System Settings_.
2. Reboot, to be sure the change is picked up.
3. When updates are available, go to _System Settings_, then _System_.

### Expected Behavior

It can display available updates, but never download them automatically; let alone prompt to install them on reboot. I have disabled Automatic Updates for a reason.

### OS Version

8.x (Circe)

### OS Architecture

amd64 (on most hardwares)

### Session Type

Secure Session (Wayland, This is the default)

### Software Version

Latest release (I have run all updates)

### Log Output

```shell

```

### Hardware Info

_No response_