[BUG] The controller does not set a readiness probe for Dashboards

[uj-ff48]

Hello,
unfortunately the operator does not set a readiness probe while deploying the opensearch dashboards component.

This makes the deployment of a GKE Ingress on Google Cloud impossible, as the ingress health check mechanism tries to reach "/" when readinessProbe.httpGet.path is not set: the usual response would be a 302 code, which is not accepted by the check (only 200 is accepted).

[prudhvigodithi]

[Triage]
Thanks @uj-ff48, is there a chance you can PR the fix?
Adding @swoehrl-mw