Improve controller readiness probe

[polskikiel]

Description

The helm-controller readiness probe is implemented in the dummy way to just return 200OK on every call.
We should return 200OK only when the controller is able to work.

We need to find the best way to implement the checking of the controller status.

Ideas:

• In SBU controller we do the test reconcile with the empty object and we expect it to process in order to indicate the readiness of the controller.
• We can wait until the controller-runtime probes implementation is ready and use it. ✨ added health probes kubernetes-sigs/controller-runtime#419