fix(test/tap): dead cleanup label in mysql_hostgroup_attributes_config_file-t.cpp

Same pattern as the sibling servers_defaults test: -Wunused-label
flagged the 'cleanup:' block, which held the only restore-from-backup
path for the mysql_hostgroup_attributes runtime table. Nothing ever
jumped to it, so every MYSQL_QUERY_T early-return from the test body
skipped the restore and leaked the admin MYSQL* handle.

- Add mysql_init NULL check and close admin on real_connect failure.
- Introduce a run_cleanup_and_exit lambda that performs the
  DELETE/INSERT restore (conditional on backup_created) and closes
  admin.
- Replace the MYSQL_QUERY_T backup-creation calls with explicit
  mysql_query_t + run_cleanup_and_exit so any failure goes through
  the cleanup path.
- Delete the dead 'cleanup:' label.

test/tap/tests/mysql_hostgroup_attributes_config_file-t.cpp

@@ -235,24 +235,56 @@ int main(int, char**) {
 	}
 
 	MYSQL* admin = mysql_init(NULL);
+	if (!admin) {
+		fprintf(stderr, "File %s, line %d, Error: mysql_init failed for admin\n",
+			__FILE__, __LINE__);
+		return EXIT_FAILURE;
+	}
 
 	if (!mysql_real_connect(admin, cl.host, cl.admin_username, cl.admin_password, NULL, cl.admin_port, NULL, 0)) {
 		fprintf(stderr, "File %s, line %d, Error: %s\n", __FILE__, __LINE__, mysql_error(admin));
+		mysql_close(admin);
 		return EXIT_FAILURE;
 	}
 
-	// For cleanup
-	MYSQL_QUERY_T(admin, "DROP TABLE IF EXISTS mysql_hostgroup_attributes_0508");
-	MYSQL_QUERY_T(admin, "CREATE TABLE mysql_hostgroup_attributes_0508 AS SELECT * FROM mysql_hostgroup_attributes");
+	// Track whether the backup table has been created; only then should
+	// the restore path run.
+	bool backup_created = false;
+	// Runs the restore (if the backup exists) and closes admin. Every
+	// error path after the backup is created must go through this lambda;
+	// the previous version had a 'cleanup:' label nothing ever jumped to,
+	// which meant every test failure leaked admin and left the
+	// mysql_hostgroup_attributes table corrupted for downstream tests.
+	auto run_cleanup_and_exit = [&]() -> int {
+		if (backup_created) {
+			if (mysql_query_t(admin, "DELETE FROM mysql_hostgroup_attributes")) {
+				fprintf(stderr, "File %s, line %d, Error: %s\n",
+					__FILE__, __LINE__, mysql_error(admin));
+			}
+			if (mysql_query_t(admin, "INSERT INTO mysql_hostgroup_attributes SELECT * FROM mysql_hostgroup_attributes_0508")) {
+				fprintf(stderr, "File %s, line %d, Error: %s\n",
+					__FILE__, __LINE__, mysql_error(admin));
+			}
+		}
+		mysql_close(admin);
+		return exit_status();
+	};
+
+	// For cleanup: create a backup of the current runtime state. Use
+	// explicit mysql_query_t so failures go through run_cleanup_and_exit
+	// rather than being swallowed by MYSQL_QUERY_T's early return.
+	if (mysql_query_t(admin, "DROP TABLE IF EXISTS mysql_hostgroup_attributes_0508")) {
+		fprintf(stderr, "File %s, line %d, Error: %s\n", __FILE__, __LINE__, mysql_error(admin));
+		return run_cleanup_and_exit();
+	}
+	if (mysql_query_t(admin, "CREATE TABLE mysql_hostgroup_attributes_0508 AS SELECT * FROM mysql_hostgroup_attributes")) {
+		fprintf(stderr, "File %s, line %d, Error: %s\n", __FILE__, __LINE__, mysql_error(admin));
+		return run_cleanup_and_exit();
+	}
+	backup_created = true;
 
 	validate_mysql_hostgroup_attributes_from_config(admin);
 	write_mysql_hostgroup_attributes_to_config(admin);
 
-cleanup:
-
-	MYSQL_QUERY_T(admin, "DELETE FROM mysql_hostgroup_attributes");
-	MYSQL_QUERY_T(admin, "INSERT INTO mysql_hostgroup_attributes SELECT * FROM mysql_hostgroup_attributes_0508");
-	mysql_close(admin);
-
-	return exit_status();
+	return run_cleanup_and_exit();
 }