Use the "minimal" packages list, rather than the "standard" one.

The "standard" list includes, in addition to the "minimal" one:

  * console-setup console-common kbd: problematic, as plymouth conflicts with
    console-common; if one of the other two packages is pulled by some
    dependency, fair enough; else, let's say we probably don't need it.
  * locales: provided by the locales-all package, that we explicitly install.