Note: the original would only set the domain if
`l10n_latam_use_documents` was enabled but even if the fields are not
shown without that it doesn't make much sense to allow any document
type to be selected when latam docs are *not* being used.

In this revision, the document type is always filtered by available
types and that is only non-empty if we're using latam documents.

Task 2147923

closes odoo/odoo#40955

Signed-off-by: Xavier Morel (xmo) <xmo@odoo.com>