refactor(nomad): use the vs-vcluster repo to create the nomad namespace

Context

The purpose of this merge request is to integrate the CSCS-provided repositories with our work, replacing our own resources wherever applicable.

Impact

Replaces the nomad_namespace resource with the vs-vcluster repository.

No behavioral changes.

Test(s)

An end-to-end testing has been executed:

1. Brought up vc-shared-services on gioannidis workspace.
2. Obtained kubernetes credentials:

   gcloud container clusters get-credentials "${USER}" --location="europe-west6-b"

3. Forwarded nomad HTTP port:

   kubectl -n nomad port-forward services/nomad-ilb 4646:4646 &

4. Brought up vclusters on gioannidis workspace.
5. Verified the resource:

   $ terraform show
   ...
   # module.vcluster1.module.vcluster.module.nomad_namespace.nomad_namespace.vcluster_namespace[0]:
   resource "nomad_namespace" "vcluster_namespace" {
   description = "Namespace for the gioannidis-1 vCluster"
       id          = "gioannidis-1"
       meta        = {
           "owner" = "hpc-systems@groupes.epfl.ch"
       }
       name        = "gioannidis-1"
       quota       = null
   }

Known issues

The nomad HTTP port needs to be forwarded in order to conduct a successful end-to-end testing.

Links

• TASK#1222