Gateways not programmed after X duration

[philbrookes]

Only gateways targeted by a DNS Policy qualify for this alert.

come up with an alert query that will allow a user to specify that if the gateway is not programmed for more than Y duration an alert will fire.

This will need to be tested that it does fire when expected.

Also some details on potential causes, and how to investigate and troubleshoot.

Recreate options:

• scale down istio-controller
• on a kind cluster create too many gateways to use up the available pool of IPs.