Fix rubocop warning (#14288)

* Fix rubocop warning

* use limit variable

* use ContextCreatingMethods option

app/controllers/auth/sessions_controller.rb

@@ -46,6 +46,7 @@ class Auth::SessionsController < Devise::SessionsController
       user   = User.authenticate_with_ldap(user_params) if Devise.ldap_authentication
       user ||= User.authenticate_with_pam(user_params) if Devise.pam_authentication
       user ||= User.find_for_authentication(email: user_params[:email])
+      user
     end
   end