Add support for workload_metadata_config GKE_METADATA mode in standard clusters

[fulyagonultas]

Describe the bug
the support for workload_metadata_config is missing. We want to enable workload identity in the clusters and ensure that GKE Metadata server is enabled.

The workload_metadata_config block supports:

mode (Required) How to expose the node metadata to the workload running on the node. Accepted values are:

GKE_METADATA: Run the GKE Metadata Server on this node. The GKE Metadata Server exposes a metadata API to workloads that is compatible with the V1 Compute Metadata APIs exposed by the Compute Engine and App Engine Metadata Servers. This feature can only be enabled if workload identity is enabled at the cluster level.

[luigi-bitonti]

Did you try to use this? https://github.com/GoogleCloudPlatform/cloud-foundation-fabric/blob/master/modules/gke-nodepool/main.tf

[ludoo]

Closing this, feel free to reopen if @luigi-bitonti suggestion does not work.