Standard NLB Use Case Missing Route Table DRG Resource Attachments

[tjkervin]

The NLB use case appears to have a DRG Route Table crated without attaching it to the DRG. I think this is because the resource type is incorrect, and should instead be using the 'oci_core_drg_route_table' resource, with route rules defined using the 'oci_core_drg_route_table_route_rule' resources. This would match how the DRG NLB Use Case handles this behavior.

Without this, I'm not seeing how traffic to the web/db VCNs would reach the external NLBs to go through the firewalls.