Convert admin/settings controller specs to system specs (#31548)

spec/system/admin/settings/branding_spec.rb

@@ -0,0 +1,37 @@
+# frozen_string_literal: true
+
+require 'rails_helper'
+
+describe 'Admin::Settings::Branding' do
+  it 'Saves changes to branding settings' do
+    sign_in admin_user
+    visit admin_settings_branding_path
+
+    fill_in short_description_field,
+            with: 'new key value'
+
+    fill_in site_contact_email_field,
+            with: User.last.email
+
+    fill_in site_contact_username_field,
+            with: Account.last.username
+
+    expect { click_on submit_button }
+      .to change(Setting, :site_short_description).to('new key value')
+
+    expect(page)
+      .to have_content(success_message)
+  end
+
+  def short_description_field
+    form_label 'form_admin_settings.site_short_description'
+  end
+
+  def site_contact_email_field
+    form_label 'form_admin_settings.site_contact_email'
+  end
+
+  def site_contact_username_field
+    form_label 'form_admin_settings.site_contact_username'
+  end
+end