23.10 autoisntall shouldn't allow closing the window

[Ken VanDine]

It's possible to close the window during an autoinstall. The autoinstall will continue in the background, but that's not obvious to someone in front of the screen. Clicking the icon to launch the installer again just spins on the "Preparing Ubuntu" screen, so the user will think the install is not actually happening and they reboot to start over.

Desired behavior: Disable the close window event during autoinstall

[Sebastien Bacher (seb128)]

Closing that ubuntu-desktop-installer report since the component is deprecated. We aren't going to fix 23.10 installer bugs at this point and Noble uses ubuntu-desktop-provision, feel free to reopen/reassign to that component if that's still an issue with the noble beta image