fix(helm): use gateway container port as nginx server port

[wind0r]

What this PR does / why we need it:
The current Helm chart allows you to change the container port for the gateway deployment, but then also the whole nginx config needs to be overwritten. With this change, nginxFile is using the containerPort, so nginx is using the correct port.

Which issue(s) this PR fixes:
Didn't create an issue for this

Special notes for your reviewer:
Nothing

Checklist

• Reviewed the CONTRIBUTING.md guide (required)
• Documentation added
• Tests updated
• Title matches the required conventional commits format, see here
  • Note that Promtail is considered to be feature complete, and future development for logs collection will be in Grafana Alloy. As such, feat PRs are unlikely to be accepted unless a case can be made for the feature actually being a bug fix to existing behavior.
• Changes that require user attention or interaction to upgrade are documented in docs/sources/setup/upgrade/_index.md
• If the change is deprecating or removing a configuration option, update the deprecated-config.yaml and deleted-config.yaml files respectively in the tools/deprecated-config-checker directory. Example PR

[CLAassistant]

All committers have signed the CLA.

[jkroepke]

loki/production/helm/loki/templates/gateway/deployment-gateway-nginx.yaml

Line 62 in cef1a6b

containerPort: {{ .Values.gateway.containerPort }}

Makes sense, LGTM!