test_k8s: Display a link to the grafana pod resources on a dumps v1 TI page

I couldn't use the official extra link Airflow interface, as it does not seem to work with mapped tasks.

However, I managed to make sure the extra_links operator attribute was rendered in the UI:

Signed-off-by: Balthazar Rouberol brouberol@wikimedia.org Bug: T389927 Closes T389927