### 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
f"Connection {new_conn_id} can't be added because it already exists, "
                    f"Please rename the existing connections",
                    "warning",
                )
            else:
                dup_conn = Connection(
                    new_conn_id,
                    selected_conn.conn_type,
                    selected_conn.description,
                    selected_conn.host,
                    selected_conn.login,
                    selected_conn.password,
                    selected_conn.schema,
                    selected_conn.port,
                    selected_conn.extra,
                )
                try:
                    session.add(dup_conn)
                    session.commit()
                    flash(f"Connection {new_conn_id} added successfully.", "success")
                except IntegrityError:
                    flash(
                        f"Connection {new_conn_id} can't be added. Integrity error, "
                        f"probably unique constraint.",
                        "warning",
                    )
                    session.rollback()
        self.update_redirect()
        return redirect(self.get_redirect())
    def process_form(self, form, is_created):