Use new stripe confirm path and remove dead code

app/controllers/spree/admin/payments_controller.rb

@@ -3,8 +3,6 @@
 module Spree
   module Admin
     class PaymentsController < Spree::Admin::BaseController
-      include FullUrlHelper
-
       before_action :load_order, except: [:show]
       before_action :load_payment, only: [:fire, :show]
       before_action :load_data

app/helpers/full_url_helper.rb

@@ -1,13 +0,0 @@
-# frozen_string_literal: true
-
-module FullUrlHelper
-  def url_helpers
-    # This is how we can get the helpers with a usable root_url outside the controllers
-    Rails.application.routes.default_url_options = ActionMailer::Base.default_url_options
-    Rails.application.routes.url_helpers
-  end
-
-  def full_checkout_path
-    URI.join(url_helpers.root_url, url_helpers.checkout_path).to_s
-  end
-end

app/models/spree/gateway/stripe_sca.rb

@@ -10,8 +10,6 @@ require 'active_merchant/billing/gateways/stripe'
 module Spree
   class Gateway
     class StripeSCA < Gateway
-      include FullUrlHelper
-
       VOIDABLE_STATES = [
         "requires_payment_method", "requires_capture", "requires_confirmation", "requires_action"
       ].freeze
@@ -143,7 +141,7 @@ module Spree
 
       def options_for_authorize(money, creditcard, gateway_options)
         options = basic_options(gateway_options)
-        options[:return_url] = gateway_options[:return_url] || full_checkout_path
+        options[:return_url] = gateway_options[:return_url] || payment_gateways_confirm_stripe_url
 
         customer_id, payment_method_id =
           Stripe::CreditCardCloner.new(creditcard, stripe_account_id).find_or_clone