Implement readiness probe

[tzstoyanov]

The tracer-svc pod is responsible for serving the REST API in a Kubernetes context. On its startup, a logic for discovery of all tracer-node pods is triggered. Usually it takes some time these pods to be discovered. If an API request is received before discovering of the tracer-node pods, that request cannot be served.
Add a readiness probe of tracer-svc pod, so that the pod should not be in ready state until thetracer-node pods are discovered.