add GKE metering (now in GA) for all module and submodule versions

[gcamus59]

GKE metering is not anymore a Beta feature, it's now in General Availability.
So, the feature should be available for use in every kind of modules.

It's already available in the beta' module versions. It seems that moving the code outside from the beta_cluster IF conditions (inside the autogen repository) will enable the feature for all module versions.

After beginning work on the modification in a pull request, I saw that the parameter is not yet available in the non beta google Terraform provider (see hashicorp/terraform-provider-google#4634)

[morgante]

Thanks, this should be easy to fix once hashicorp/terraform-provider-google#4634 is resolved.

[thomas-riccardi]

hashicorp/terraform-provider-google@a646d86 is now included in google 3.16.0.

Also, would it be possible to make enable_network_egress_metering configurable (which is set to true here whereas in the provider it defaults to false)? (And maybe enable_resource_consumption_metering too for completeness).

[gcamus59]

Thanks, I'll work on it this week and I will craft a pull request.