[E2E Test] Test if target Scale-To-Zero via Prometheus Query.

[ramantehlan]

Expected Behaviour

When there is no traffic in Prometheus for a service, within a configured cooldown period.
Then Operator should scale target to Zero.

Scenario

This is just to help plan the scenario, but the actual implementation might have different steps.

1. We can keep a short cooldown period.
2. We can augment data inside prometheus via remote write or any other method, to indicate that there is no traffic received in the configured cooldown period.
3. Once the controller query the prom, it should switch the mode to proxy.
4. Assert that the mode is switched to proxy in the CRD.

Similar tests

• 01-enable-proxy-via-manual: It scales down the service manually and checks if controller is watching this event, and will switch to proxy mode or not.