fix: create pg connection for cloud-hosted jobs instead of panicking (#8710)

Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

backend/windmill-worker/src/pg_executor.rs

@@ -372,7 +372,7 @@ pub async fn do_postgresql(
         }
     } else {
         cached_client = None;
-        new_client = None;
+        new_client = Some(new_pg_connection(&database, use_iam_auth).await?);
     }
 
     let (sig, typed_schema) = parse_pgsql_sig_with_typed_schema(&query)