remove operation_log_serialize_subject

app/models/dossier_operation_log.rb

@@ -85,8 +85,6 @@ class DossierOperationLog < ApplicationRecord
   def self.serialize_subject(subject)
     if subject.nil?
       nil
-    elsif !Flipper.enabled?(:operation_log_serialize_subject)
-      { id: subject.id }
     else
       case subject
       when Dossier

config/initializers/flipper.rb

@@ -33,7 +33,6 @@ features = [
   :autosave_dossier_draft,
   :maintenance_mode,
   :mini_profiler,
-  :operation_log_serialize_subject,
   :xray,
   :carte_ign,
   :localization

spec/controllers/instructeurs/dossiers_controller_spec.rb

@@ -307,6 +307,7 @@ describe Instructeurs::DossiersController, type: :controller do
         before do
           attestation = Attestation.new
           allow(attestation).to receive(:pdf).and_return(double(read: 'pdf', size: 2.megabytes))
+          allow(attestation).to receive(:pdf_url).and_return('http://some_document_url')
 
           allow_any_instance_of(Dossier).to receive(:build_attestation).and_return(attestation)
         end