Reference public resolvers using variables

[jcralbino]

Is your feature request related to a problem? Please describe.

Users deploying orb OnPrem solutions via helm charts, need to "translate" information within the templates to match their corporate solutions. Whenever possible variables should be used that can simplify this work

Describe the solution you'd like

For example here

https://github.com/orb-community/orb-helm/blob/e1883f0fd44c19b07212669a21b3655f545e810a/charts/orb/templates/nginx-internal.yaml#L60

Instead of using public dns IPs directly "8.8.8.8" we should use a variable .

That variable should be changed afterwards to the correct resolver that allows the required resolution

Describe alternatives you've considered

Additional context

We need to assume that Orb OnPrem solutions would be deployed also in environments where internet connectivity is not granted , neither recursive resolutions. This means that all the required resources need to be obtained OnPrem also.