If a translation has an empty src and value, the value in the dictionary
after the search_read is False, not ''
When doing an insert, False is converted to 'false'
Before 489494e733 the translations were inserted using the ORM which correctly
converts False to ''
opw-1999723
closes odoo/odoo#33649
Signed-off-by: Martin Trigaux (mat) <mat@odoo.com>