### 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 = admin_client.get("users/userinfo/", follow_redirects=True)
    check_content_in_response('Your user information', resp)
def test_edit_myuserinfo(admin_client):
    resp = admin_client.post(
        "userinfoeditview/form",
        data={'first_name': 'new_first_name', 'last_name': 'new_last_name'},
        follow_redirects=True,
    )
    check_content_in_response("User information changed", resp)
@pytest.mark.parametrize(
    "url",
    ["users/add", "users/edit/1", "users/delete/1"],
    ids=["add-user", "edit-user", "delete-user"],
)
def test_views_post_access_denied(viewer_client, url):
    resp = viewer_client.get(url, follow_redirects=True)
    check_content_in_response("Access is Denied", resp)
@pytest.fixture()
def non_exist_username(app):
    username = "fake_username"
    user = app.appbuilder.sm.find_user(username)
    if user is not None:
        app.appbuilder.sm.del_register_user(user)
    yield username
    user = app.appbuilder.sm.find_user(username)
    if user is not None:
        app.appbuilder.sm.del_register_user(user)
def test_create_user(app, admin_client, non_exist_username):