fix enable annotation reply when collection is None (#2877)

Co-authored-by: jyong <jyong@dify.ai>

api/tasks/annotation/enable_annotation_reply_task.py

                 logging.info(
                     click.style('Delete annotation index error: {}'.format(str(e)),
                                 fg='red'))
-            vector.add_texts(documents)
+            vector.create(documents)
         db.session.commit()
         redis_client.setex(enable_app_annotation_job_key, 600, 'completed')
         end_at = time.perf_counter()