[php-src] PR #25297: ext/mysqlnd: Fix crash after metadata EOF failure on prepared statements

Pull Request: https://github.com/php/php-src/pull/25297 Author: iliaal If the server sends a short EOF packet after a prepared statement's column definitions, or closes the connection there, mysqli_stmt::prepare() after stmt_init(), mysqli_stmt::execute(), and PDOStatement::execute() crash: mysqlnd_stmt_prepare_read_eof() and mysqlnd_query_read_result_set_header() memset the whole statement on that failure, so the next errno or error access dereferences NULL. Free only the result instead and report the failure, as CR_MALFORMED_PACKET for a short EOF and as the connection error copied to the statement for a failed prepare. A failed execute still leaves the connection in CONN_FETCHING_DATA and the statement open on the server, as it did before this change.