[IMP] website_mass_mailing: remove horizontal scrollbar in popup

Sometimes while dropping a newsletter popup (for ex in blogs, events etc),
there's a horizontal scroll-bar on the pop-up due to bootstrap gutters.

This commit improves the behavior by removing the gutters on the div causing
the horizontal scroll-bar on the popup.

Task-ID - 2312996

closes odoo/odoo#61855

Signed-off-by: Thibault Delavallee (tde) <tde@openerp.com>

addons/website_mass_mailing/views/snippets_templates.xml

@@ -64,7 +64,7 @@
     </section>
     <section class="s_text_block" data-snippet="s_text_block">
         <div class="container">
-            <div class="row s_nb_column_fixed">
+            <div class="row s_nb_column_fixed no-gutters">
                 <div class="col-lg-8 offset-lg-2 pt32 pb32">
                     <t t-snippet-call="website_mass_mailing.s_newsletter_subscribe_form"/>
                 </div>