Fix XWiki automation bootstrap:

- Accept HTTP 302 (Distribution Wizard redirects) in REST readiness and extension checks
- Treat 302 as missing admin user during bootstrap
- Move superadmin password to xwiki.cfg (correct location)
- Disable automatic Distribution Wizard start in xwiki.properties
- Standardize run_once includes for postgres, cdn, and xwiki roles

See: https://chatgpt.com/share/68c3a67b-80b4-800f-8a90-ebdcd4abb86c

roles/svc-db-postgres/tasks/01_core.yml

@@ -25,3 +25,5 @@
   community.general.pacman:
     name: python-psycopg2
     state: present
+
+- include_tasks: utils/run_once.yml

roles/svc-db-postgres/tasks/main.yml

@@ -1,6 +1,5 @@
 - block:
   - include_tasks: 01_core.yml
-  - include_tasks: utils/run_once.yml
     vars:
       # Force the flush of the pg handler on the first run
       flush_handlers: true