Remove display name input from sign-up form (#24704)

app/views/auth/registrations/new.html.haml

@@ -19,7 +19,6 @@
 
   .fields-group
     = f.simple_fields_for :account do |ff|
-      = ff.input :display_name, wrapper: :with_label, label: false, required: false, input_html: { 'aria-label': t('simple_form.labels.defaults.display_name'), autocomplete: 'off', placeholder: t('simple_form.labels.defaults.display_name') }
       = ff.input :username, wrapper: :with_label, label: false, required: true, input_html: { 'aria-label': t('simple_form.labels.defaults.username'), autocomplete: 'off', placeholder: t('simple_form.labels.defaults.username'), pattern: '[a-zA-Z0-9_]+', maxlength: 30 }, append: "@#{site_hostname}"
     = f.input :email, placeholder: t('simple_form.labels.defaults.email'), required: true, input_html: { 'aria-label': t('simple_form.labels.defaults.email'), autocomplete: 'username' }, hint: false
     = f.input :password, placeholder: t('simple_form.labels.defaults.password'), required: true, input_html: { 'aria-label': t('simple_form.labels.defaults.password'), autocomplete: 'new-password', minlength: User.password_length.first, maxlength: User.password_length.last }, hint: false