feat: startupProbe to avoid a long initial delay seconds for liveness probe

[a7i]

https://kubernetes.io/docs/tasks/configure-pod-container/configure-liveness-readiness-startup-probes/

Kubernetes Docs:

The kubelet uses startup probes to know when a container application has started. If such a probe is configured, liveness and readiness probes do not start until it succeeds, making sure those probes don't interfere with the application startup. This can be used to adopt liveness checks on slow starting containers, avoiding them getting killed by the kubelet before they are up and running.

[a7i]

readiness probe must fail before liveness probe. otherwise container stops receiving traffic and restarts at the same time.

[a7i]

ideally you should run readiness as soon as the container comes up

[lmello]

we were having issues in our environment, when we reduced the liveness probe timeout.

This change solves the issue in a more efficent way.

In the worst case scenario kubernetes wait up to 160 seconds for container start, but it will proceed as soon as the container pass the probe.

Best case scenario if it starts fast it will wait only 10 seconds.

This allows kubernetes to wait for the container startup in a more efficient way, soon as the container starts, then it benefits of a faster liveness probe and readiness probe.