Simplify feature loop in welcome mailer (#29760)

app/views/application/mailer/_feature.html.haml

@@ -11,10 +11,8 @@
                 %table.email-w-full{ cellspacing: 0, cellpadding: 0, border: 0, role: 'presentation' }
                   %tr
                     %td.email-column-td
-                      - if defined?(feature_title)
+                      %h2.email-h2= t("user_mailer.welcome.feature_#{feature}_title")
-                        %h2.email-h2= feature_title
+                      %p.email-p= t("user_mailer.welcome.feature_#{feature}")
-                      - if defined?(feature_text)
-                        %p.email-p= feature_text
                       - if defined?(feature_btn_url)
                         = link_to '', href: feature_btn_url, class: 'email-link-with-arrow' do
                           #{t('user_mailer.welcome.feature_action')} 
@@ -25,8 +23,8 @@
                 %table.email-w-full{ cellspacing: 0, cellpadding: 0, border: 0, role: 'presentation' }
                   %tr
                     %td.email-column-td
-                      - if defined?(key)
+                      - if defined?(feature)
                         %p{ class: ('email-desktop-text-right' if defined?(text_first_on_desktop) && text_first_on_desktop) }
-                          = image_tag frontend_asset_url("images/mailer-new/welcome/#{key}.png"), alt: '', width: 240, height: 230
+                          = image_tag frontend_asset_url("images/mailer-new/welcome/feature_#{feature}.png"), alt: '', width: 240, height: 230
               /[if mso]
                 </td></tr></table>

app/views/user_mailer/welcome.html.haml

@@ -68,7 +68,7 @@
 %table.email-w-full{ cellspacing: 0, cellpadding: 0, border: 0, role: 'presentation' }
   %tr
     %td.email-extra-td
-      = render 'application/mailer/feature', key: 'feature_control', feature_title: t('user_mailer.welcome.feature_control_title'), feature_text: t('user_mailer.welcome.feature_control'), text_first_on_desktop: true
+      = render 'application/mailer/feature', feature: 'control', text_first_on_desktop: true
-      = render 'application/mailer/feature', key: 'feature_audience', feature_title: t('user_mailer.welcome.feature_audience_title'), feature_text: t('user_mailer.welcome.feature_audience'), text_first_on_desktop: false
+      = render 'application/mailer/feature', feature: 'audience', text_first_on_desktop: false
-      = render 'application/mailer/feature', key: 'feature_moderation', feature_title: t('user_mailer.welcome.feature_moderation_title'), feature_text: t('user_mailer.welcome.feature_moderation'), text_first_on_desktop: true
+      = render 'application/mailer/feature', feature: 'moderation', text_first_on_desktop: true
-      = render 'application/mailer/feature', key: 'feature_creativity', feature_title: t('user_mailer.welcome.feature_creativity_title'), feature_text: t('user_mailer.welcome.feature_creativity'), text_first_on_desktop: false
+      = render 'application/mailer/feature', feature: 'creativity', text_first_on_desktop: false