feature: allow custom labels in helm chart for Ray workerGroup

[JustinDuy]

Describe the feature

We have a small request to allow custom labels for Ray workerGroup. Our current situation is that we have a default istio side car injection to all pods, only can be disabled by specifying labels: "sidecar.istio.io/inject: "false". Unfortunately currently, there is no way to do that for the workerGroup: https://github.com/vllm-project/production-stack/blob/main/helm/templates/ray-cluster.yaml#L258

Why do you need this feature?

vllm engine initialization inside ray head got stuck because the istio-proxy container inside ray worker intercepts all traffic. As a result, we can't start vllm engine with ray pipeline parallel.

Additional context

Ray head custom label are passed via engineLabels: https://github.com/vllm-project/production-stack/blob/main/helm/templates/ray-cluster.yaml#L24 -> that should apply to workerGroup too in my opinion

[JustinDuy]

Ray head log with 'peer reset connection to 172.31.226.15:44299' and istio-proxy log with that traffic

[JustinDuy]

@ahinsutime, @YuhanLiu11: if it's fine with you, i can add the code.

[YuhanLiu11]

@JustinDuy sure! Please submit the PR with the added code. Thanks!

[JustinDuy]

@YuhanLiu11 : could you please take a look at the MR? Thank you!