We don't have a readiness check on the operator, so OCP reports it as ready as soon as it is up, which is not quite true: it takes a few moments for it to initialize webhooks etc. We should add a real readiness check to avoid having to sleep in tests (see e.g. https://github.com/maistra/istio-operator/pull/814#discussion_r689812955)

Acceptance Criteria:

• Create a real readiness check endpoint (e.g. /ready)
• Make sure it only returns 200 OK when the operator is fully operational (ie all controllers have synced and webhook certs for CRDs have been updated)