Unable to set locale when using interactive-sections in Automated Installs

[Pedro Principeza]

[Description]
When using the `interactive-sections` [0] setting in Automated Server Installations, it is documented that `locale` automatically becomes interactive as a consequence [1].

However, if one tries to make `locale` an automated option (i.e. defining the `locale` setting to be used during that install), such setting is ignored, and the installation stops and asks you for that definition.

[Impact]
Whenever a user tries to have one single interactive section to pop-up during the installation, that'll add an undesired "freebie" locale step to be filled in.

[Reproduction Steps]
Create a schema that contains:

interactive-sections:
- <add any section here>

And define, moreover:

locale: <locale>

The locale definitions will still be inquired during the installation.

[ . . . ]

[0] https://ubuntu.com/server/docs/install/autoinstall-reference#interactive-sections
[1] https://ubuntu.com/server/docs/install/autoinstall-reference#locale

[Michael Hudson-Doyle (mwhudson)]

Ah I remember one of the reasons I did this: currently the locale screen is where the logic to ask the user if they want to use "rich mode" on a serial connection lives and that's a question that should be asked even for a partially interactive autoinstall. I think if we can move that logic to somewhere more generic then it should be fine to skip the locale screen.