fix: Custom registryCredentialsConfig in helmCharts of kof-istio

[denis-ryzhkov]

• kof-istio does not use ServiceTemplates (where we added cert/secretRefs already) because it needs dependsOn feature not supported by MCS yet.
• Despite CASecretRef mentioned in https://projectsveltos.github.io/sveltos/addons/helm_charts/#example-private-registry the expected JSON field name is ca - https://github.com/projectsveltos/addon-controller/blob/v0.57.2/api/v1beta1/spec.go#L167
• Testing with values:

  kcm:
    kof:
      repo:
        spec:
          secretRef:
            name: foo
          certSecretRef:
            name: bar
  

• Result:

  kubectl get ClusterProfile -o yaml | grep -C5 registryCredentialsConfig
  
      helmCharts:
      - chartName: kof/kof-operators
        chartVersion: 1.2.0
        helmChartAction: Install
        registryCredentialsConfig:
          ca:
            name: bar
          credentials:
            name: foo
        releaseName: kof-operators
  --
      - chartName: kof/kof-collectors
        chartVersion: 1.2.0
        helmChartAction: Install
        registryCredentialsConfig:
          ca:
            name: bar
          credentials:
            name: foo
        releaseName: kof-collectors
  --
      - chartName: cert-manager
        chartVersion: v1.16.4
        helmChartAction: Install
        registryCredentialsConfig:
          ca:
            name: bar
          credentials:
            name: foo
        releaseName: cert-manager
  

  and 5 more, OK.