### 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)

@task_group
            def tg2(inp):
                another_task(inp, val)  # val here should resolve to [2, 4, 6].
            tg2.expand(inp=["a", "b"])
        The surrounding mapped task groups of ``upstream`` and ``self.task`` are
        inspected to find a common "ancestor". If such an ancestor is found,
        we need to return specific map indexes to pull a partial value from
        upstream XCom.
        :param upstream: The referenced upstream task.
        :param ti_count: The total count of task instance this task was expanded
            by the scheduler, i.e. ``expanded_ti_count`` in the template context.
        :return: Specific map index or map indexes to pull, or ``None`` if we
            want to "whole" return value (i.e. no mapped task groups involved).
        """
        
        
        
        
        
        if not ti_count:
            return None
        
        
        
        
        common_ancestor = _find_common_ancestor_mapped_group(self.task, upstream)
        if common_ancestor is None:
            return None