[DBM][Postgres] Debug log if extension is not in loader map (DataDog#21891)

* Added pg_stat_statement to PG_EXTENSION_LOADER_QUERY

* Updated query

* Updated code based on discussion with Engineering

Author: aldrickdev

postgres/datadog_checks/postgres/metadata.py

@@ -812,13 +812,13 @@ def _collect_postgres_settings(self):
                         if row['schemaname'] in ['pg_catalog', 'public']:
                             query = PG_EXTENSION_LOADER_QUERY[extension] + "\n" + query
                         else:
-                            self._log.warning(
+                            self._log.debug(
                                 "unable to collect settings for extension %s in schema %s",
                                 extension,
                                 row['schemaname'],
                             )
                     else:
-                        self._log.warning("unable to collect settings for unknown extension %s", extension)
+                        self._log.debug("unable to collect settings for unknown extension %s", extension)
 
                 if self.pg_settings_ignored_patterns:
                     query = query + " WHERE name NOT LIKE ALL(%s)"