### Description

expanding tasks in batches to allow mapped tasks spawn more than 1024 processes.

### Use case/motivation

Maximum length of a list is limited to 1024 by `max_map_length (AIRFLOW__CORE__MAX_MAP_LENGTH)`.
during scheduling of the new tasks, an UPDATE query is ran that tries to set all the new tasks at once.  Increasing `max_map_length` more than 4K makes airflow scheduler completely unresponsive.

Also, Postgres throws `stack depth limit exceeded` error which can be fixed by updating to a newer version and setting `max_stack_depth` higher. But it doesn't really matter because airflow scheduler freezes up.
 
As a workaround, I split the dag runs into subdag runs which works but it would be much nicer if we didn't have to worry about exceeding  `max_map_length`. 

### Related issues

It was discussed here:
[Increasing 'max_map_length' leads to SQL 'max_stack_depth' error with 5000 dags to be spawned #28478](https://github.com/apache/airflow/discussions/28478)

### Are you willing to submit a PR?

- [ ] Yes I am willing to submit a PR!

### Code of Conduct

- [X] I agree to follow this project's [Code of Conduct](https://github.com/apache/airflow/blob/main/CODE_OF_CONDUCT.md)

return  
        except NotFullyPopulated:
            return  
        query = session.query(TI.map_index).filter(
            TI.dag_id == self.dag_id,
            TI.task_id == task.task_id,
            TI.run_id == self.run_id,
        )
        existing_indexes = {i for (i,) in query}
        removed_indexes = existing_indexes.difference(range(total_length))
        if removed_indexes:
            session.query(TI).filter(
                TI.dag_id == self.dag_id,
                TI.task_id == task.task_id,
                TI.run_id == self.run_id,
                TI.map_index.in_(removed_indexes),
            ).update({TI.state: TaskInstanceState.REMOVED})
            session.flush()
        for index in range(total_length):
            if index in existing_indexes:
                continue
            ti = TI(task, run_id=self.run_id, map_index=index, state=None)
            self.log.debug("Expanding TIs upserted %s", ti)
            task_instance_mutation_hook(ti)
            ti = session.merge(ti)
            ti.refresh_from_task(task)
            session.flush()
            yield ti
    @staticmethod
    def get_run(session: Session, dag_id: str, execution_date: datetime) -> DagRun | None: