chore(haproxy): streamline service port configuration for flexibility

[matthisholleville]

Refactored the service port configuration in the HAProxy Helm chart to allow for more flexible and deterministic exposure of ports. This change introduces a new exposedPorts option in values.yaml, which, when specified, takes precedence over the default container ports for service exposure. This enhancement facilitates clearer and more customizable service definitions, catering to diverse deployment scenarios.

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In my case, this feature enables me to expose a port within the pods to configure peers without exposing this port through my service.

For my service, I only want to expose ports 80, 443, and a few others.

[tuxillo]

@matthisholleville could you please share how you would go about the peers configuration with your PR? As far as I know, if you have for example a Deployment, each pod of the ReplicaSet must become a peer.