Fixes #37011 - Apply latest Ubuntu Autoinstall userdata changes

[bastian-src]

As mentioned in the ticket, the latest version of Ubuntu Autoinstall introduces some changes. Therefore, the following adaptions are made:

• Add explicit fallback for offline installation
• Replace deprecated lock-passwd with lock_passwd
• Remove empty ssh keys array if none provided

Still, Autoinstall deployment will fail at the moment, due to #10036

[bastian-src]

Webpack tests seem unrelated.