change: ip_range_services to optional value (#1949)

[martin-kulich-whalebone]

Based on #1989 by @0Delta , fixed the comments that were not addressed in the original PR and updated tests.

Fixes #1949.

As of GKE version 1.29 and Autopilot 1.27, the service ip range is given a default of 34.118.224.0/20 per cluster.
Versions earlier than the specified version may be omitted, but will be rejected by the validator.

This change has a big impact, but has not been thoroughly discussed yet.
We hope to merge it after sufficient discussion and making the necessary corrections.

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[apeabody]

Thanks for the contribution @martin-kulich-whalebone!

A few findings from the initial LINT:

terraform_validate ./examples/simple_autopilot_private
╷
│ Error: Reference to undeclared local value
│ 
│   on network.tf line 45, in module "gcp-network":
│   45:         range_name    = local.svc_range_name
│ 
│ A local value with the name "svc_range_name" has not been declared.
╵
terraform_validate ./examples/simple_regional_private
╷
│ Error: Reference to undeclared input variable
│ 
│   on test_outputs.tf line 52, in output "ip_range_services":
│   52:   value       = var.ip_range_services
│ 
│ An input variable with the name "ip_range_services" has not been declared.
│ This variable can be declared with a variable "ip_range_services" {} block.
╵
terraform_validate ./test/fixtures/simple_autopilot_private
╷
│ Error: Reference to undeclared local value
│ 
│   on ../../../examples/simple_autopilot_private/network.tf line 45, in module "gcp-network":
│   45:         range_name    = local.svc_range_name
│ 
│ A local value with the name "svc_range_name" has not been declared.
╵
terraform_validate ./test/fixtures/simple_regional_private
╷
│ Error: Unsupported argument
│ 
│   on example.tf line 26, in module "example":
│   26:   ip_range_services              = google_compute_subnetwork.main.secondary_ip_range[1].range_name
│ 
│ An argument named "ip_range_services" is not expected here.

[apeabody]

/gcbrun

[apeabody]

Can we verify these conditions (using variables) are supported in Terraform v1.3 (currently the minimum required version).

[apeabody]

Thanks for the contribution @martin-kulich-whalebone!

Please verify the condition syntax works with Terraform v1.3

[apeabody]

Suggested change

	error_message = "The ip_range_services is require for this gke version. Please set ip_range_services or use kubernetes_version 1.27 or upper."
	error_message = "Setting ip_range_services is require for this GKE version. Please set ip_range_services or use kubernetes_version 1.27 or later."

[apeabody]

Suggested change

	error_message = "The ip_range_services is require for this gke version. Please set ip_range_services or use kubernetes_version 1.29 or upper."
	error_message = "Setting ip_range_services is require for this GKE version. Please set ip_range_services or use kubernetes_version 1.29 or later."