Fix omniauth SAML patch

Patch the omniauth-saml gem in an initializer instead of
relying on the autoloader to overwrite the class

lib/omni_auth/strategies/saml.rb → config/initializers_before_autoloader/100_patch_omniauth_saml.rb

 # frozen_string_literal: true
 
+require 'omniauth/strategies/saml'
+
 module OmniAuth
   module Strategies
     class SAML
-      extend ::Gitlab::Utils::Override
-
       # NOTE: This method duplicates code from omniauth-saml
       #       so that we can access authn_request to store it
       #       See: https://github.com/omniauth/omniauth-saml/issues/172
-      override :request_phase
       def request_phase
         authn_request = OneLogin::RubySaml::Authrequest.new
 

spec/lib/omni_auth/strategies/saml_spec.rb → spec/initializers/100_patch_omniauth_saml_spec.rb

@@ -2,7 +2,7 @@
 
 require 'spec_helper'
 
-describe OmniAuth::Strategies::SAML, type: :strategy do
+describe 'OmniAuth::Strategies::SAML', type: :strategy do
   let(:idp_sso_target_url) { 'https://login.example.com/idp' }
   let(:strategy) { [OmniAuth::Strategies::SAML, { idp_sso_target_url: idp_sso_target_url }] }