[IMP] mass_mailing: rating snippet improved

Changed `h4` to `h3`.
Removed padding when inside another snippet which already has its own
padding.

Part-of: odoo/odoo#95940

addons/mass_mailing/static/src/snippets/s_rating/001.scss

@@ -1,3 +1,7 @@
+.o_mail_snippet_general .s_rating{
+    padding-left: 0!important;
+    padding-right: 0!important;
+}
 
 .s_rating[data-vcss="001"] {
     &.s_rating_inline {

addons/mass_mailing/views/snippets/s_rating.xml

@@ -2,8 +2,8 @@
 <odoo>
 
 <template id="s_rating" name="Rating">
-    <div class="s_rating pt16 pb16 px-3 o_mail_snippet_general" data-vcss="001" data-icon="fa-star" data-snippet="s_rating">
-        <h4 class="s_rating_title">Quality</h4>  
+    <div class="s_rating o_mail_snippet_general pt16 pb16 px-3" data-vcss="001" data-icon="fa-star" data-snippet="s_rating">
+        <h3>Quality</h3>
         <div class="s_rating_icons o_not_editable">
             <span class="s_rating_active_icons">
                 <i class="fa fa-star"></i>