Allow more flexible host/port treatment with LOCAL_DOMAIN values in tests (#35040)

spec/system/profile_spec.rb

@@ -5,8 +5,6 @@ require 'rails_helper'
 RSpec.describe 'Profile' do
   include ProfileStories
 
-  let(:local_domain) { Rails.configuration.x.local_domain }
-
   before do
     as_a_logged_in_user
     Fabricate(:user, account: Fabricate(:account, username: 'alice'))
@@ -16,7 +14,7 @@ RSpec.describe 'Profile' do
     visit account_path('alice')
 
     expect(page)
-      .to have_title("alice (@alice@#{local_domain})")
+      .to have_title("alice (@alice@#{local_domain_uri.host})")
   end
 
   it 'I can change my account' do