fix: duplicate MultiClusterService rendering when Istio is disabled

[mcd01]

This PR fixes an issue where the Helm templates in kof-child and kof-regional would always iterate over both true and false for the Istio loop, even when istio.enabled was set to false.

As a result, the chart rendered duplicate MultiClusterService resources with identical IDs, causing Kustomize reconciliation failures (already registered id):

status:
  conditions:
    - lastTransitionTime: '2026-02-20T08:56:38Z'
      message: >-
        Helm upgrade failed for release kof/kof-regional with chart
        kof-regional@1.7.1: error while running post render on files: may not
        add resource with an already registered id:
        MultiClusterService.v1beta1.k0rdent.mirantis.com/kof-regional-cluster.[noNs]

Change

Updated the loop logic to conditionally build the iteration list based on $.Values.istio.enabled:

• When istio.enabled = true → iterate over true and false (existing behavior)
• When istio.enabled = false → iterate only over false

This prevents duplicate manifests from being rendered while preserving the intended behavior when Istio is enabled.

Impact

• Fixes Helm failures due to duplicate resource IDs
• Keeps backward-compatible behavior when Istio is enabled
• Applies consistently to both kof-child and kof-regional

Suggestion

Include this fix as part of a patch-release to make kof usable again in non-istio setups. Otherwise, if I am not mistaken, it is currently a hard blocker.

[denis-ryzhkov]

Thanks! We'll wait for CI, then merge this PR, and include it in the KOF 1.8.0 to be released soon on 2026-03-02, so I guess there is no need to make a patch release.