Support helm chart server separate liveness and readiness probe endpoints

### Issue
Latest pinot helm chart doesn't support separate liveness and readiness probe endpoint for server ([link](https://github.com/apache/pinot/blob/master/helm/pinot/values.yaml#L311-L314)) (both use `server.probes.endpoint`) but the service underneath supports it ([link](https://github.com/apache/pinot/pull/9031)) .

### Proposal
Add supports for `server.probes.livenessEndpoint` and `server.probes.readinessEndpoint` to helm chart server sts template, but make it backward compatible by falling back to the existing `server.probes.endpoint`.

Start with helm/pinot/values.yaml around the existing server.probes.endpoint setting, then locate the Helm chart server StatefulSet (STS) template. Add separate livenessEndpoint and readinessEndpoint values while preserving fallback to the existing endpoint. Done means the generated probes use the separate values when set and remain backward compatible when they are absent.

Written by the indexing model from the issue text.