fix broken radius role

Would crash if called from anything other than the nuke radius DBs
playbook

roles/radius/tasks/main.yml

@@ -123,7 +123,7 @@
   systemd:
     name: freeradius
     state: stopped
-  when: nuke_radius|bool
+  when: nuke_radius|default(false)
 
 - name: Nuking - Remove old subscription if it exists
   community.general.postgresql_subscription:
@@ -131,7 +131,7 @@
     db: re2o
     state: absent
   become_user: postgres
-  when: nuke_radius|bool
+  when: nuke_radius|default(false)
   ignore_errors: yes
 
 - name: Nuking - Destroy old local DB if it exists
@@ -139,7 +139,7 @@
     name: re2o
     state: absent
   become_user: postgres
-  when: nuke_radius|bool
+  when: nuke_radius|default(false)
 
 - name: Create local DB
   community.general.postgresql_db: