### Description

https://github.com/apache/airflow/pull/17946 implements a `/robots.txt` endpoint to block search engines crawling Airflow - in the cases where it is (accidentally) exposed to the public Internet.

If we record any GET requests to that end-point we'd have a strong warning flag that the deployment is exposed, and could issue a warning in the UI, or even enable some kill-switch on the deployment. 

Some deployments are likely intentionally available and rely on auth mechanisms on the `login` endpoint, so there should be a config option to suppress the warnings.

An alternative approach would be to monitor for requests from specific user-agents used by crawlers for the same reasons

### Use case/motivation

People who accidentally expose airflow have a slightly higher chance of realising they've done so and tighten their security.

### Related issues

_No response_

### 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)

airflow/www/views.py
]
        children_end_dates = [
            item['end_date'] for item in child_instances if item['run_id'] == dag_run.run_id
        ]
        children_states = [item['state'] for item in child_instances if item['run_id'] == dag_run.run_id]
        group_state = None
        for state in priority:
            if state in children_states:
                group_state = state
                break
        group_start_date = wwwutils.datetime_to_string(
            min((timezone.parse(date) for date in children_start_dates if date), default=None)
        )
        group_end_date = wwwutils.datetime_to_string(
            max((timezone.parse(date) for date in children_end_dates if date), default=None)
        )
        return {
            'task_id': task_group.group_id,
            'run_id': dag_run.run_id,
            'state': group_state,
            'start_date': group_start_date,
            'end_date': group_end_date,
        }
    group_summaries = [get_summary(dr, children) for dr in dag_runs]
    return {
        'id': task_group.group_id,
        'label': task_group.label,
        'children': children,
        'tooltip': task_group.tooltip,
        'instances': group_summaries,