### 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)

tests/www/views/test_views_base.py
role_name = "test_roles_create_role"
    delete_role_if_exists(role_name)
    yield role_name
    delete_role_if_exists(role_name)
@pytest.fixture()
def exist_role_name(app, delete_role_if_exists):
    role_name = "test_roles_create_role_new"
    app.appbuilder.sm.add_role(role_name)
    yield role_name
    delete_role_if_exists(role_name)
@pytest.fixture()
def exist_role(app, exist_role_name):
    return app.appbuilder.sm.find_role(exist_role_name)
def test_roles_create(app, admin_client, non_exist_role_name):
    admin_client.post("roles/add", data={'name': non_exist_role_name}, follow_redirects=True)
    assert app.appbuilder.sm.find_role(non_exist_role_name) is not None
def test_roles_create_unauthorized(app, viewer_client, non_exist_role_name):
    resp = viewer_client.post("roles/add", data={'name': non_exist_role_name}, follow_redirects=True)
    check_content_in_response('Access is Denied', resp)
    assert app.appbuilder.sm.find_role(non_exist_role_name) is None
def test_roles_edit(app, admin_client, non_exist_role_name, exist_role):
    admin_client.post(
        f"roles/edit/{exist_role.id}", data={'name': non_exist_role_name}, follow_redirects=True
    )
    updated_role = app.appbuilder.sm.find_role(non_exist_role_name)
    assert exist_role.id == updated_role.id
def test_roles_edit_unauthorized(app, viewer_client, non_exist_role_name, exist_role_name, exist_role):