Helm and Operator Release Improvements

[prudhvigodithi]

Description

Coming from initial PR #872.

Fix the error https://github.com/opensearch-project/opensearch-k8s-operator/actions/runs/11685891300/job/32540910915

Looking up latest tag...
Discovering changed charts since 'v2.6.0'...
WARNING: charts/opensearch-cluster/templates/Chart.yaml is missing, assuming that 'charts/opensearch-cluster/templates' is not a Helm chart. Skipping.
Nothing to do. No chart changes detected.

Since moving from stefanprodan/helm-gh-pages@master to helm/[email protected] added fetch-depth and skip_existing. The skip_existing should not throw an error if the chart with same version is already added to the gh-pages branch index.yaml file.

Here are some tests done on my fork

Release Helm Charts workflow

https://github.com/prudhvigodithi/opensearch-k8s-operator/actions/workflows/helm-release.yaml

Publish Release from tag workflow

https://github.com/prudhvigodithi/opensearch-k8s-operator/actions/runs/11687219955

Issues Resolved

Coming from #830

Check List

• Commits are signed per the DCO using --signoff
• Unittest added for the new/changed functionality and all unit tests are successful
• Customer-visible features documented
• No linter warnings (make lint)

If CRDs are changed:

• CRD YAMLs updated (make manifests) and also copied into the helm chart
• Changes to CRDs documented

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