Simplify class field when logging bulk arguments

In https://gitlab.com/gitlab-org/gitlab/-/merge_requests/73223/diffs, we
were previously logging a Hash of elements for `class` when we really
just needed the class name. The mismatched types was causing
Elasticsearch to drop these log messages.

app/workers/concerns/application_worker.rb

@@ -145,12 +145,12 @@ module ApplicationWorker
 
     def bulk_perform_async(args_list)
       if log_bulk_perform_async?
-        Sidekiq.logger.info('class' => self, 'args_list' => args_list, 'args_list_count' => args_list.length, 'message' => 'Inserting multiple jobs')
+        Sidekiq.logger.info('class' => self.name, 'args_list' => args_list, 'args_list_count' => args_list.length, 'message' => 'Inserting multiple jobs')
       end
 
       do_push_bulk(args_list).tap do |job_ids|
         if log_bulk_perform_async?
-          Sidekiq.logger.info('class' => self, 'jid_list' => job_ids, 'jid_list_count' => job_ids.length, 'message' => 'Completed JID insertion')
+          Sidekiq.logger.info('class' => self.name, 'jid_list' => job_ids, 'jid_list_count' => job_ids.length, 'message' => 'Completed JID insertion')
         end
       end
     end

spec/workers/concerns/application_worker_spec.rb

@@ -355,9 +355,9 @@ RSpec.describe ApplicationWorker do
         worker.log_bulk_perform_async!
 
         expect(Sidekiq.logger).to(
-          receive(:info).with(hash_including('args_list' => args)).once.and_call_original)
+          receive(:info).with(hash_including('class' => worker.name, 'args_list' => args)).once.and_call_original)
         expect(Sidekiq.logger).to(
-          receive(:info).with(hash_including('jid_list' => anything)).once.and_call_original)
+          receive(:info).with(hash_including('class' => worker.name, 'jid_list' => anything)).once.and_call_original)
 
         perform_action
       end