MDEV-5386: Server crashes in thd_get_ha_data on maria-5.5-galera tree while running 'check testcase before test

Analysis: In Galera binlog is not enabled by default in case
when wsrep provider is not specified. In this case we should
not call thd->binlog_flush_pending_rows_event(TRUE). 

Fix: Added a additional guard on galera not to call binlog
function if wsrep provider is not specified and binlog is
not enabled.