xwiki: switch to PostgreSQL and remove custom Hibernate override

Config: set database.type=postgres; use image tag lts-<dbtype>-tomcat; make DB_TYPE templated; derive database_type from app config.

Cleanup: delete hibernate.cfg.xml template and volume mounts; remove XWIKI_HOST_HIBERNATE_PATH; stop rendering hibernate.cfg.xml.

web-svc-cdn: run_once task fix.

Context: troubleshooting on 2025-09-12. Conversation link: https://chatgpt.com/share/68c3978e-77cc-800f-beda-19220f70855f

roles/web-app-xwiki/config/main.yml

@@ -5,9 +5,10 @@ docker:
       enabled:      false
     database:
       enabled:      true
+      type:         postgres
     xwiki:
       image:        xwiki
-      version:      stable-mariadb-tomcat
+      version:      lts-<< defaults_applications[web-app-xwiki].docker.services.database.type >>-tomcat
       name:         xwiki
       backup:
         no_stop_required: true