Helm chart: Explicitly describe the exposed port

[hsudbrock]

Describe the feature
In the Helm chart for connaisseur, explicitly specify the port exposed by the container port (cf. https://kubernetes.io/docs/reference/generated/kubernetes-api/v1.28/#containerport-v1-core).

Optional: Is your feature request related to a problem? Please describe.
As described in #709, prometheus has issues scraping metrics from connaisseur, because the metrics are exposed via HTTPS, and prometheus cannot validate the HTTPS certificate. To circumvent this problem, one option is to tell prometheus to skip certificate validation (which is, for some, ok for metrics scraping), e.g., using a PodMonitor from the prometheus operator. But: PodMonitors require the port they scrape to be specified explicitly for the container.

Note that using the already provided service to scrape metrics is not an option, because in case of a HA deployment of connaisseur each scrape call might go to different pods.

I will provide a MR for this, it's a small change.