Update dnsNameservers context to pick up values

[dalees]

The dnsNameservers value has moved into managedSubnets section, but was trying to reference .internalNetwork.dnsNameservers which does not exist in chart values.

This change removes the context switch into internalNetwork to allow all references to correctly find their related values.

Closes: #476

[dalees]

@mkjpryor If there is a better approach here than removing the context change with, please let me know. I'll be happy to update this PR.

It would be nice to move the .Values field, but I'm not sure how to do that in Helm, in a backwards compatible way.

[mkjpryor]

@dalees

I was also thinking that the fix here should probably be to move the values field into internalNetwork, since it is only respected by the managed subnet.

In order to maintain backwards compatibility, I think we just have to replace

{{- with .dnsNameservers }}

with

{{- with (default $.Values.clusterNetworking.dnsNameservers .dnsNameservers) }}

and modify values.yaml to move the field into internalNetwork?

[dalees]

Ah thanks, @mkjpryor - that was a lot easier than what I was thinking of.

I wasn't sure of the best practice around referencing values outside the current scope.

Updated the PR to use your suggestion and moved the values field.