fix(global_defaults): normalize disks when install_drive is supplied externally

roles/global_defaults/tasks/_normalize_disks.yml

@@ -94,6 +94,7 @@
 
     - name: Set install_drive from primary disk
       when:
+        - install_drive is not defined
         - system_disks_cfg | length > 0
         - system_disks_cfg[0].device | string | length > 0
       ansible.builtin.set_fact:

roles/global_defaults/tasks/system.yml

@@ -79,9 +79,7 @@
     os_version: "{{ system_cfg.version | default('') | string }}"
 
 - name: Normalize disk configuration (pre-computed system_cfg)
-  when:
-    - system_cfg is defined
-    - install_drive is not defined
+  when: system_cfg is defined
   ansible.builtin.include_tasks: _normalize_disks.yml
 
 # Runs on every path before validation, so an empty firewall.backend / content.source