use AC autoconf discovery end_session_endpoint

app/controllers/users/sessions_controller.rb

@@ -110,6 +110,6 @@ class Users::SessionsController < Devise::SessionsController
 
   def build_agent_connect_logout_url(id_token)
     h = { id_token_hint: id_token, post_logout_redirect_uri: logout_url }
-    "#{ENV['AGENT_CONNECT_BASE_URL']}/api/v2/session/end?#{h.to_query}"
+    "#{AGENT_CONNECT[:end_session_endpoint]}?#{h.to_query}"
   end
 end

spec/controllers/users/sessions_controller_spec.rb

@@ -85,6 +85,7 @@ describe Users::SessionsController, type: :controller do
     let(:agent_connect_id_token) { nil }
 
     before do
+      stub_const("AGENT_CONNECT", { end_session_endpoint: 'http://agent-connect/logout' })
       sign_in user
       delete :destroy
     end