Remove admin_user helper method from SystemHelpers module (#34096)

spec/system/admin/terms_of_service/drafts_spec.rb

@@ -3,6 +3,8 @@
 require 'rails_helper'
 
 RSpec.describe 'Admin TermsOfService Drafts' do
+  let(:admin_user) { Fabricate(:admin_user) }
+
   before { sign_in(admin_user) }
 
   describe 'Managing TOS drafts' do

spec/system/admin/terms_of_service/generates_spec.rb

@@ -3,6 +3,8 @@
 require 'rails_helper'
 
 RSpec.describe 'Admin TermsOfService Generates' do
+  let(:admin_user) { Fabricate(:admin_user) }
+
   before { sign_in(admin_user) }
 
   describe 'Generating a TOS policy' do

spec/system/admin/terms_of_service/previews_spec.rb

@@ -4,6 +4,7 @@ require 'rails_helper'
 
 RSpec.describe 'Admin TermsOfService Previews' do
   let(:terms_of_service) { Fabricate(:terms_of_service, notification_sent_at: nil) }
+  let(:admin_user) { Fabricate(:admin_user) }
 
   before { sign_in(admin_user) }