Use correct attribute name for ACR

[bobalong79]

ACR entries are stored as azure_container_registries in the state file. This PR corrects the attribute name so that an ACR declared in a remote lz can be used.

e.g.

{
  "outputs":{
    "objects":{
      "value":{
        "lz_key":{
          "azure_container_registries":{
            "acr1":{ ... }
          }
        }
      }
    }
  }
}

PR Checklist

---

• I have updated the documentation accordingly.
• I have added tests to cover my changes.
• All new and existing tests passed.
• My code follows the code style of this project.
• I ran lint checks locally prior to submission.
• Have you checked to ensure there aren't other open Pull Requests for the same update/change?

Description

Does this introduce a breaking change

• YES
• NO

Testing

Try referencing an ACR declared in a remote lz, e.g. for role mapping

role_mapping = {
  built_in_role_mapping = {
    azure_container_registries = {
      acr1 = {
        lz_key = "remote_lz"
        "AcrPull" = {
          aks_clusters = {
            keys = ["cluster_re1"]
          }
        }
      }
    }
  }
}

[arnaudlh]

Good catch, LGTM