### 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)

self, exception: BaseException, task: BaseOperator | None = None
    ) -> tuple[str, str, str]:
        """Get the email subject content for exceptions."""
        
        if task is None:
            task = getattr(self, "task")
        use_default = task is None
        exception_html = str(exception).replace("\n", "<br>")
        default_subject = "Airflow alert: {{ti}}"
        
        
        
        default_html_content = (
            "Try {{try_number}} out of {{max_tries + 1}}<br>"
            "Exception:<br>{{exception_html}}<br>"
            'Log: <a href="{{ti.log_url}}">Link</a><br>'
            "Host: {{ti.hostname}}<br>"
            'Mark success: <a href="{{ti.mark_success_url}}">Link</a><br>'
        )
        default_html_content_err = (
            "Try {{try_number}} out of {{max_tries + 1}}<br>"
            "Exception:<br>Failed attempt to attach error logs<br>"
            'Log: <a href="{{ti.log_url}}">Link</a><br>'
            "Host: {{ti.hostname}}<br>"
            'Mark success: <a href="{{ti.mark_success_url}}">Link</a><br>'