Code review comment for ~mfo/ubiquity:automatic_prepare

The OEM enablement team is apparently OK with the changes, but will need a few days to verify their tooling for any impacts.

They have recovery functionality that adds plugin(s) to ubiquity, and that is what needs testing w/ these changes.

I have clarified that the impact of the new version (w/out the option to gate the page from showing up or not) is just the page showing up in automatic mode now, and that can be skipped by preseeding 'ubiquity/use_nonfree', in their case probably to 'false', so it doesn't install any 3rd party drivers as they may likely be doing that in a later step already.

cheers,
Mauricio