### 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
resp = viewer_client.post(
        f"roles/edit/{exist_role.id}", data={'name': non_exist_role_name}, follow_redirects=True
    )
    check_content_in_response('Access is Denied', resp)
    assert app.appbuilder.sm.find_role(exist_role_name)
    assert app.appbuilder.sm.find_role(non_exist_role_name) is None
def test_roles_delete(app, admin_client, exist_role_name, exist_role):
    admin_client.post(f"roles/delete/{exist_role.id}", follow_redirects=True)
    assert app.appbuilder.sm.find_role(exist_role_name) is None
def test_roles_delete_unauthorized(app, viewer_client, exist_role, exist_role_name):
    resp = viewer_client.post(f"roles/delete/{exist_role.id}", follow_redirects=True)
    check_content_in_response('Access is Denied', resp)
    assert app.appbuilder.sm.find_role(exist_role_name)
@pytest.mark.parametrize(
    "url, client, content",
    [
        ("userstatschartview/chart/", "admin_client", "User Statistics"),
        ("userstatschartview/chart/", "viewer_client", "Access is Denied"),
        ("actions/list", "admin_client", "List Actions"),
        ("actions/list", "viewer_client", "Access is Denied"),
        ("resources/list/", "admin_client", "List Resources"),
        ("resources/list/", "viewer_client", "Access is Denied"),
        ("permissions/list/", "admin_client", "List Permissions"),
        ("permissions/list/", "viewer_client", "Access is Denied"),
        ("resetpassword/form?pk=1", "admin_client", "Reset Password Form"),
        ("resetpassword/form?pk=1", "viewer_client", "Access is Denied"),
        ("users/list", "admin_client", "List Users"),
        ("users/list", "viewer_client", "Access is Denied"),