fix(postgres-system): Fix dashboard variables

This renames some labels used in queries to match the results from the
podMonitor instead of relying on additional labels set by the exporter.

infrastructure/postgres/dashboards/postgresql-database.json

@@ -3032,7 +3032,7 @@
         "options": [],
         "query": "query_result(pg_exporter_last_scrape_duration_seconds)",
         "refresh": 2,
-        "regex": "/.*kubernetes_namespace=\"([^\"]+).*/",
+        "regex": "/.*exported_namespace=\"([^\"]+).*/",
         "skipUrlSync": false,
         "sort": 1,
         "tagValuesQuery": "",
@@ -3052,9 +3052,9 @@
         "multi": false,
         "name": "release",
         "options": [],
-        "query": "query_result(pg_exporter_last_scrape_duration_seconds{kubernetes_namespace=\"$namespace\"})",
+        "query": "query_result(pg_exporter_last_scrape_duration_seconds{exported_namespace=\"$namespace\"})",
         "refresh": 2,
-        "regex": "/.*release=\"([^\"]+)/",
+        "regex": "/.*cluster_name=\"([^\"]+)/",
         "skipUrlSync": false,
         "sort": 1,
         "tagValuesQuery": "",