Make namespace deletions log an event per project deletion

app/services/groups/destroy_service.rb

 module Groups
   class DestroyService < Groups::BaseService
     def async_execute
-      # Soft delete via paranoia gem
-      group.destroy
+      # Don't call `group.destroy` since this will purge all the projects, which may be too slow
+      group.deleted_at = Time.now
       job_id = GroupDestroyWorker.perform_async(group.id, current_user.id)
       Rails.logger.info("User #{current_user.id} scheduled a deletion of group ID #{group.id} with job ID #{job_id}")
     end

spec/services/ee/groups/destroy_service_spec.rb

@@ -10,10 +10,17 @@ describe Groups::DestroyService, services: true do
     group.add_user(user, Gitlab::Access::OWNER)
   end
 
-  it 'creates a Geo event log for each project deleted' do
+  it 'creates a Geo event log when project is deleted synchronously' do
     Groups::DestroyService.new(group, user).execute
 
     expect(Geo::EventLog.count).to eq(1)
     expect(Geo::RepositoryDeletedEvent.count).to eq(1)
   end
+
+  it 'creates a Geo event log when project is deleted asynchronously' do
+    Sidekiq::Testing.inline! { Groups::DestroyService.new(group, user).async_execute }
+
+    expect(Geo::EventLog.count).to eq(1)
+    expect(Geo::RepositoryDeletedEvent.count).to eq(1)
+  end
 end