[IMP] tools: ignore line number for code translations

The line number was only indicative and was not used by the system.
When the translations source were updated, a big part of the diff was
only about the line numbers.
Ignore the given res_id value and export the line at 0

When reading the po file, the res_id from the file is still read and
stored in database but should be ignored

closes odoo/odoo#35582

Signed-off-by: Martin Trigaux (mat) <mat@odoo.com>