feat: allow default node pools metadata key-value pairs to be disabled

[caueasantos]

Resolves #2004

There are many ways to go about this, but I tried to quickly expose a way for users to disable default metadata labels added by the module.

First time opening a pull request here, let me know if I missed anything.

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[apeabody]

Thanks for the contribution @caueasantos!

Should this change apply to Autopilot cluster?

Working in ./modules/beta-autopilot-private-cluster ...
1 issue(s) found:

Warning: [Fixable] variable "enable_default_node_pools_metadata" is declared but not used (terraform_unused_declarations)

  on variables.tf line 427:
 427: variable "enable_default_node_pools_metadata" {

Reference: https://github.com/terraform-linters/tflint-ruleset-terraform/blob/v0.7.0/docs/rules/terraform_unused_declarations.md

tflint failed ./modules/beta-autopilot-private-cluster 
Working in ./modules/beta-autopilot-public-cluster ...
1 issue(s) found:

Warning: [Fixable] variable "enable_default_node_pools_metadata" is declared but not used (terraform_unused_declarations)

  on variables.tf line 397:
 397: variable "enable_default_node_pools_metadata" {

Reference: https://github.com/terraform-linters/tflint-ruleset-terraform/blob/v0.7.0/docs/rules/terraform_unused_declarations.md

tflint failed ./modules/beta-autopilot-public-cluster 

[caueasantos]

Thanks for the contribution @caueasantos!

Should this change apply to Autopilot cluster?

Working in ./modules/beta-autopilot-private-cluster ...
1 issue(s) found:

Warning: [Fixable] variable "enable_default_node_pools_metadata" is declared but not used (terraform_unused_declarations)

  on variables.tf line 427:
 427: variable "enable_default_node_pools_metadata" {

Reference: https://github.com/terraform-linters/tflint-ruleset-terraform/blob/v0.7.0/docs/rules/terraform_unused_declarations.md

tflint failed ./modules/beta-autopilot-private-cluster 
Working in ./modules/beta-autopilot-public-cluster ...
1 issue(s) found:

Warning: [Fixable] variable "enable_default_node_pools_metadata" is declared but not used (terraform_unused_declarations)

  on variables.tf line 397:
 397: variable "enable_default_node_pools_metadata" {

Reference: https://github.com/terraform-linters/tflint-ruleset-terraform/blob/v0.7.0/docs/rules/terraform_unused_declarations.md

tflint failed ./modules/beta-autopilot-public-cluster 

Definitely not, let me see how I can disable the variable for autopilot clusters using the autogeneration templates.

[apeabody]

/gcbrun

[apeabody]

/gcbrun