[Enhancement][opensearch-dashboards] Add service.protocol parameter to set protocol type

[enes-zed]

Is your feature request related to a problem? Please describe.
I'd like to add for opensearch-dashboards Helm chart the ability to specify the service.protocol type through values.yaml, which is currently hardcoded as TCP. This will particularly be useful for deployments e.g. on Istio, which in current setting does not parse/route the traffic correctly.

Describe the solution you'd like

• Parameterize the service template file for service.protocol to default to TCP (current behavior) but allow for setting e.g. HTTP through values.yaml

Describe alternatives you've considered
Alternatively there is a workaround by renaming the port from http to tcp, which will make Istio work, but this then has the side-effect that the traffic is not parsed instead just passed through.

Additional context
No other context present.