fix: Propagate Namespace correctly to Helm

[Skaronator]

Summary

This PR introduces a bugfix for issue #5566, which is currently the 6th most upvoted issue in the Kustomize repository.

Bugfix Details

The fix modifies how namespace values are handled within kustomization.yaml when using helmCharts:

• If a namespace is set at the top level of the kustomization.yaml, it will always be propagated to the Helm CLI command.
• However, if a helmCharts entry specifies its own namespace, that value takes precedence and overrides the top-level one.

NamespaceTransformer Behavior

Additionally, the NamespaceTransformer will now skip all manifests generated by Helm charts. This aligns with the principle that Helm charts should manage their own namespaces internally.

This change also enables charts to deploy resources across multiple namespaces—an essential capability for many popular charts such as the cert-manager Helm chart, which installs RBAC resources into the kube-system namespace.

[k8s-ci-robot]

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[k8s-ci-robot]

Hi @Skaronator. Thanks for your PR.

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[Skaronator]

@koba1t Could you please take a look on this and do /ok-to-test command? Most of the CI Jobs already run anyway but tide and kustomize-presubmit-master are stuck - not sure why.

[prnv30]

hi @ncapps @varshaprasad96 @koba1t this PR addresses a bugfix for #5566 , which is a highly upvoted issue at the moment. It’s been open for a while, so could we please review and prioritize it? Thanks!