Refactor appeal partial to avoid brakeman XSS warning (#25880)

spec/controllers/admin/disputes/appeals_controller_spec.rb

@@ -18,10 +18,14 @@ RSpec.describe Admin::Disputes::AppealsController do
   describe 'GET #index' do
     let(:current_user) { Fabricate(:user, role: UserRole.find_by(name: 'Admin')) }
 
-    it 'lists appeals' do
+    before { appeal }
+
+    it 'returns a page that lists details of appeals' do
       get :index
 
-      expect(response).to have_http_status(200)
+      expect(response).to have_http_status(:success)
+      expect(response.body).to include("<span class=\"username\">#{strike.account.username}</span>")
+      expect(response.body).to include("<span class=\"target\">#{appeal.account.username}</span>")
     end
   end