### 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
if not execution_date:
            flash('Invalid execution date', 'error')
            return redirect(origin)
        execution_date = timezone.parse(execution_date)
        dag = current_app.dag_bag.get_dag(dag_id)
        if not dag:
            flash(f'Cannot find DAG: {dag_id}', 'error')
            return redirect(origin)
        new_dag_state = set_dag_run_state_to_success(dag, execution_date, commit=confirmed)
        if confirmed:
            flash(f'Marked success on {len(new_dag_state)} task instances')
            return redirect(origin)
        else:
            details = '\n'.join(str(t) for t in new_dag_state)
            response = self.render_template(
                'airflow/confirm.html',
                message="Here's the list of task instances you are about to mark as success",
                details=details,
            )
            return response
    @expose('/dagrun_failed', methods=['POST'])
    @auth.has_access(
        [
            (permissions.ACTION_CAN_EDIT, permissions.RESOURCE_DAG),
            (permissions.ACTION_CAN_EDIT, permissions.RESOURCE_DAG_RUN),
        ]
    )
    @action_logging
    def dagrun_failed(self):