Remove more hardcoded matrix-postgres references

roles/custom/matrix-bridge-mautrix-hangouts/tasks/validate_config.yml

@@ -1,14 +1,12 @@
 ---
 
-- name: Fail if required settings not defined
+- name: Fail if required mautrix-hangouts settings not defined
   ansible.builtin.fail:
     msg: >-
-      You need to define a required configuration setting (`{{ item }}`).
-  when: "vars[item] == ''"
+      You need to define a required configuration setting (`{{ item.name }}`).
+  when: "item.when | bool and vars[item.name] == ''"
   with_items:
-    - "matrix_mautrix_hangouts_public_endpoint"
-    - "matrix_mautrix_hangouts_appservice_token"
-    - "matrix_mautrix_hangouts_homeserver_token"
-- ansible.builtin.debug:
-    msg:
-      - '`matrix_mautrix_hangouts_homeserver_domain` == {{ matrix_mautrix_hangouts_homeserver_domain }}'
+    - {'name': 'matrix_mautrix_hangouts_public_endpoint', when: true}
+    - {'name': 'matrix_mautrix_hangouts_appservice_token', when: true}
+    - {'name': 'matrix_mautrix_hangouts_homeserver_token', when: true}
+    - {'name': 'matrix_mautrix_hangouts_database_hostname', when: "{{ matrix_mautrix_hangouts_database_engine == 'postgres' }}"}