lib: remove the 'migrated' key on filters

In a9a4f6e2a8, a task to migrate
ProcedurePresentation's filters was added.

This task added a "migrated: true" key to all migrated filters.

Now that this task has run, we can safely remove the extra key.

spec/lib/tasks/deployment/20210720133539_remove_migration_status_on_filters_spec.rb

@@ -0,0 +1,45 @@
+describe '20201001161931_migrate_filters_to_use_stable_id' do
+  let(:rake_task) { Rake::Task['after_party:remove_migration_status_on_filters'] }
+
+  let(:procedure) { create(:simple_procedure) }
+  let(:instructeur_1) { create(:instructeur) }
+  let(:instructeur_2) { create(:instructeur) }
+
+  let(:assign_to_1) { create(:assign_to, procedure: procedure, instructeur: instructeur_1) }
+  let(:assign_to_2) { create(:assign_to, procedure: procedure, instructeur: instructeur_2) }
+
+  let(:procedure_presentation_with_migration) { create(:procedure_presentation, assign_to: assign_to_1, filters: filters.merge('migrated': true)) }
+  let(:procedure_presentation_without_migration) { create(:procedure_presentation, assign_to: assign_to_2, filters: filters) }
+
+  let(:filters) do
+    { "suivis" => [{ "table" => "user", "column" => "email", "value" => "test@example.com" }] }
+  end
+
+  before do
+    procedure_presentation_with_migration
+    procedure_presentation_without_migration
+
+    rake_task.invoke
+
+    procedure_presentation_with_migration.reload
+    procedure_presentation_without_migration.reload
+  end
+
+  after { rake_task.reenable }
+
+  context 'when the procedure presentation has a "migrated" key' do
+    it 'removes the "migrated" key' do
+      expect(procedure_presentation_with_migration.filters).not_to have_key('migrated')
+    end
+
+    it 'leaves other keys unchanged' do
+      expect(procedure_presentation_with_migration.filters['suivis']).to be_present
+    end
+  end
+
+  context 'when the procedure presentation doesn’t have a "migrated" key' do
+    it 'leaves keys unchanged' do
+      expect(procedure_presentation_without_migration.filters['suivis']).to be_present
+    end
+  end
+end