Fix variable name typo in validation task

roles/custom/matrix_playbook_migration/tasks/validate_config.yml

@@ -133,7 +133,7 @@
     - {'old': 'matrix_prometheus_services_proxy_connect_prometheus_node_exporter_metrics_proxying_enabled', 'new': '<removed>'}
     - {'old': 'matrix_prometheus_services_proxy_connect_prometheus_node_exporter_matrix_nginx_proxy_not_enabled_proxy_pass_host', 'new': '<removed>'}
     - {'old': 'matrix_prometheus_services_proxy_connect_prometheus_postgres_exporter_metrics_proxying_enabled', 'new': '<removed>'}
-    - {'old': 'matrix_prometheus_services_proxy_connect_prometheus_postgres_exporter_metrics_proxying_enabledmatrix_prometheus_services_proxy_connect_prometheus_postgres_exporter_metrics_proxying_enabled', 'new': '<removed>'}
+    - {'old': 'matrix_prometheus_services_proxy_connect_prometheus_postgres_exporter_matrix_nginx_proxy_not_enabled_proxy_pass_host', 'new': '<removed>'}
 
 - name: (Deprecation) Catch and report matrix_postgres variables
   ansible.builtin.fail: