models: add a Procedure#with_hidden scope, and remove unscoped usages

This avoids the broad use of `unscoped` to remove the `hidden_at`
clause.

lib/tasks/2017_10_18_regenerate_attestation.rake

@@ -12,7 +12,7 @@ namespace :'2017_10_18_regenerate_attestation' do
   end
 
   def regenerate_attestations(attestation)
-    Procedure.unscoped do
+    Procedure.with_hidden do
       Dossier.unscoped do
         dossier = attestation.dossier
         procedure = dossier.procedure

lib/tasks/2018_05_15_add_aasm_state_to_procedure.rake

@@ -3,6 +3,6 @@ namespace :'2018_05_15_add_aasm_state_to_procedure' do
     Procedure.archivees.update_all(aasm_state: :archivee)
     Procedure.publiees.update_all(aasm_state: :publiee)
     Procedure.brouillons.update_all(aasm_state: :brouillon)
-    Procedure.unscoped.where.not(hidden_at: nil).update_all(aasm_state: :hidden)
+    Procedure.rewhere(hidden_at: nil).update_all(aasm_state: :hidden)
   end
 end

lib/tasks/deployment/20190704133852_create_dummy_paths_for_archived_and_hidden_procedures.rake

@@ -3,11 +3,11 @@ namespace :after_party do
   task create_dummy_paths_for_archived_and_hidden_procedures: :environment do
     rake_puts "Running deploy task 'create_dummy_paths_for_archived_procedures'"
 
-    Procedure.unscoped.archivees.where(path: nil).each do |p|
+    Procedure.with_hidden.archivees.where(path: nil).each do |p|
       p.update_column(:path, SecureRandom.uuid)
     end
 
-    Procedure.unscoped.hidden.where(path: nil).each do |p|
+    Procedure.hidden.where(path: nil).each do |p|
       p.update_column(:path, SecureRandom.uuid)
     end
 

lib/tasks/deployment/20190819142551_create_default_groupe_instructeur.rake

@@ -2,7 +2,7 @@ namespace :after_party do
   desc 'Deployment task: create_default_groupe_instructeur'
   task create_default_groupe_instructeur: :environment do
     Procedure
-      .unscoped
+      .with_hidden
       .left_outer_joins(:groupe_instructeurs)
       .where('groupe_instructeurs.id is null')
       .find_each do |procedure|