Taxes on self-invoices for non-EU export actually have amount > 0,
l10n_it_has-exoneration = False but they must have the law reference
field filled out, so we're taking the "invisible" clause
out of the view.

Task: https://www.odoo.com/web#id=3010849&model=project.task


opw-3010849

closes odoo/odoo#105036

X-original-commit: 825bb40c
Signed-off-by: Josse Colpaert <jco@odoo.com>
Signed-off-by: Paolo Gatti (pgi) <pgi@odoo.com>