[Bug]: Fix race condition when deploying Charmed HPC

[NucciTheBoss]

There current exists a race condition with how Terraform constructs the deployment plan for Charmed HPC.

The issue is caused by us referring to the model name as regular string rather than as a Terraform resource. When parallelism is enabled, sometimes the Charmed HPC deployment will fail, however, if we do not use parallelism - terraform apply -auto-approve -parallelism=1- the Terraform will succeed at deploying the Charmed HPC cloud.

Possible fix

Refer to model name using a Terraform resource rather than as a regular string:

# Instead of this
model = var.model_name

# Do this instead
model = juju_model.charmed-hpc.name

Relevant screenshots

Race conditions being shown by Terraform: