Install playbook now fails if Terraform is not already installed

[AlexCK-STFC]

I'm not sure why this is an issue now, perhaps an upstream update. But the install playbook now produces a string, not a list, for terraform_available_versions if no versions are present, causing the Filter terraform versions task to fail:

Using /home/ubuntu/azimuth/cloud-azimuth-config/environments/stfc-dev/ansible.cfg as config file
running playbook inside collection azimuth_cloud.azimuth_ops

PLAY [Provision seed node using OpenTofu] **************************************

TASK [Gathering Facts] *********************************************************
ok: [localhost]

TASK [Install Terraform] *******************************************************
included: azimuth_cloud.terraform.install for localhost

TASK [azimuth_cloud.terraform.install : Check if Terraform binary exists in search directories] ***
ok: [localhost] => (item=/home/ubuntu/azimuth/cloud-azimuth-config/.bin) => {"ansible_loop_var": "item", "changed": false, "item": "/home/ubuntu/azimuth/cloud-azimuth-config/.bin", "stat": {"exists": false}}
ok: [localhost] => (item=/home/ubuntu/azimuth/cloud-azimuth-config/.venv/bin) => {"ansible_loop_var": "item", "changed": false, "item": "/home/ubuntu/azimuth/cloud-azimuth-config/.venv/bin", "stat": {"exists": false}}
ok: [localhost] => (item=/usr/local/sbin) => {"ansible_loop_var": "item", "changed": false, "item": "/usr/local/sbin", "stat": {"exists": false}}
ok: [localhost] => (item=/usr/local/bin) => {"ansible_loop_var": "item", "changed": false, "item": "/usr/local/bin", "stat": {"exists": false}}
ok: [localhost] => (item=/usr/sbin) => {"ansible_loop_var": "item", "changed": false, "item": "/usr/sbin", "stat": {"exists": false}}
ok: [localhost] => (item=/usr/bin) => {"ansible_loop_var": "item", "changed": false, "item": "/usr/bin", "stat": {"exists": false}}
ok: [localhost] => (item=/sbin) => {"ansible_loop_var": "item", "changed": false, "item": "/sbin", "stat": {"exists": false}}
ok: [localhost] => (item=/bin) => {"ansible_loop_var": "item", "changed": false, "item": "/bin", "stat": {"exists": false}}
ok: [localhost] => (item=/usr/games) => {"ansible_loop_var": "item", "changed": false, "item": "/usr/games", "stat": {"exists": false}}
ok: [localhost] => (item=/usr/local/games) => {"ansible_loop_var": "item", "changed": false, "item": "/usr/local/games", "stat": {"exists": false}}
ok: [localhost] => (item=/snap/bin) => {"ansible_loop_var": "item", "changed": false, "item": "/snap/bin", "stat": {"exists": false}}

TASK [azimuth_cloud.terraform.install : Get available Terraform versions] ******
skipping: [localhost] => {"changed": false, "skipped_reason": "No items in the list"}

TASK [azimuth_cloud.terraform.install : Set Terraform versions fact] ***********
ok: [localhost] => {"ansible_facts": {"terraform_available_versions": "[\n  ]"}, "changed": false}

TASK [azimuth_cloud.terraform.install : Filter Terraform versions] *************
[ERROR]: Task failed: Finalization of task args for 'ansible.builtin.set_fact' failed: Error while resolving value for 'terraform_acceptable_versions': object of type 'str' has no attribute 1

Task failed.
Origin: /home/ubuntu/azimuth/cloud-azimuth-config/.ansible/collections/ansible_collections/azimuth_cloud/terraform/roles/install/tasks/main.yml:26:3

24       ]
25
26 - name: Filter Terraform versions
     ^ column 3

<<< caused by >>>

Finalization of task args for 'ansible.builtin.set_fact' failed.
Origin: /home/ubuntu/azimuth/cloud-azimuth-config/.ansible/collections/ansible_collections/azimuth_cloud/terraform/roles/install/tasks/main.yml:27:3

25
26 - name: Filter Terraform versions
27   ansible.builtin.set_fact:
     ^ column 3

<<< caused by >>>

Error while resolving value for 'terraform_acceptable_versions': object of type 'str' has no attribute 1
Origin: /home/ubuntu/azimuth/cloud-azimuth-config/.ansible/collections/ansible_collections/azimuth_cloud/terraform/roles/install/tasks/main.yml:28:36

26 - name: Filter Terraform versions
27   ansible.builtin.set_fact:
28     terraform_acceptable_versions: >-
                                      ^ column 36

fatal: [localhost]: FAILED! => {"changed": false, "msg": "Task failed: Finalization of task args for 'ansible.builtin.set_fact' failed: Error while resolving value for 'terraform_acceptable_versions': object of type 'str' has no attribute 1"}

PLAY RECAP *********************************************************************
localhost                  : ok=4    changed=0    unreachable=0    failed=1    skipped=1    rescued=0    ignored=0   

N.B: ok: [localhost] => {"ansible_facts": {"terraform_available_versions": "[\n ]"}, "changed": false}

PR incoming to fix, assuming this issue is reproducible.