Fix firewall update logic for -1

[zliang-akamai]

📝 Description

-1 represents explicit no firewall now. We need to handle it in the update logic.

✔️ How to Test

Install the collection in this branch

make install

Then run this playbook twice:

ansible-playbook /path/to/the/test_playbook.yaml

- name: Test Firewall ID
  hosts: localhost
  collections:
    - linode.cloud
  tasks:
    - name: Create a Linode instance
      linode.cloud.instance:
        label: example-linode
        type: g6-nanode-1
        region: us-central
        image: linode/arch
        root_pass: ReplaceWithAStrwediedekro3ouijqklongPassword123!
        state: present
        firewall_id: -1
        booted: false
      register: create_linode
  environment:
    LINODE_API_VERSION: v4beta

[mgwoj]

Should we have a test for this case?

[lgarber-akamai]

@zliang-akamai Will this case be covered by the existing tests once the change rolls out in the API?