Drop the Helm chart lint job

[ru-sh]

The lint-helm job points kubeconform at the chart directory:

kubeconform ci/helm-chart

kubeconform reads those files as plain YAML, but the templates are Go
templates, so every one of them fails to parse regardless of what the chart
contains:

ci/helm-chart/templates/pvc.yaml - failed validation: error unmarshalling resource: error converting YAML to JSON: yaml: did not find expected node content
ci/helm-chart/templates/service.yaml - failed validation: ... yaml: line 5: did not find expected node content
ci/helm-chart/Chart.yaml - failed validation: error while parsing: missing 'kind' key
ci/helm-chart/values.yaml - failed validation: error while parsing: missing 'kind' key

The job is gated on ci/helm-chart/**, so it only runs when the chart changes
and has gone unnoticed. It surfaced on #3, a three-line version bump, where it
was the only red check.

Rendering first (helm template ci/helm-chart | kubeconform -) would make it
work, but #4 establishes that this chart is published nowhere and is bumped by
hand. A lint that has never passed, guarding an unpublished artifact, costs
more as noise on every future chart bump than it returns, so it is removed
rather than fixed.

The helm paths-filter and the helm output on the changes job go with it —
lint-helm was their only consumer.

🤖 Generated with Claude Code