[FIX] website_mass_mailing: fix newsletters names in newsletter web block

Steps to reproduce:

- Install website_mass_mailing
- Go to the frontend and activate the editor.
- Add a newsletter block, change it to subscription form.

Issue: The name of the newsletter is displaying also the number of
subscribers (e.g. "Newsletter (1)").

Solution: Change the name we are using to display the newsletter name to
use the `name` and not the `display_name`.

opw-3145571

closes odoo/odoo#117846

X-original-commit: 3930df6c06197b70a019caa4d6782453095a7c66
Signed-off-by: Thibault Delavallee (tde) <tde@openerp.com>

addons/website_mass_mailing/views/snippets_templates.xml

@@ -101,7 +101,7 @@ database, without the s_newsletter_list class. See fixNewsletterListClass.
                                                 <input type="checkbox" class="s_website_form_input form-check-input" name="list_ids"
                                                     t-attf-id="mailing_list_#{record.id}" t-att-value="record.id" required="1"/>
                                                 <label class="form-check-label s_website_form_check_label" t-attf-for="mailing_list_#{record.id}">
-                                                    <t t-esc="record.display_name"/>
+                                                    <t t-esc="record.name"/>
                                                 </label>
                                             </div>
                                         </div>