[FIX] account: manage unique constraint violation in taxes update

Some databases encounter an error when they try to upgrade when
they have more than one tax with the same name that violate
the tax name unique constraint (name, company_id, type_tax_use, tax_scope).
This will adapt the update of taxes script to handle this situation
by renaming such taxes to [old] taxname, [old1] taxname, etc.

opw-3178128

closes odoo/odoo#117771

Signed-off-by: Quentin De Paoli <qdp@odoo.com>
Signed-off-by: Claire Bretton <clbr@odoo.com>