Mailing model holds a convert_links method that converts its local links.
It is not used in standard flows as it has more used for external tools.
Indeed sending mailings effectively shorten links without going through
that method.
However sms mailings are not supported by this method. In this commit we
ensure calling this method effectively convert links for sms mailings.
Same as email mailings links in standard flows are already shortened.
This allows notably to fix demo data as links were not converted
correctly as it was calling convert_links in xml.
Task ID-2274770
PR odoo/odoo#56887
Related: odoo/upgrade#1744
Signed-off-by: Thibault Delavallee (tde) <tde@openerp.com>