Zabbix

........S. [ZBX-20232] added HA node table cleanup on startup

Merge in ZBX/zabbix from feature/ZBX-20232-5.5 to master

* commit '15c11166d877ccbbd0d17e918f352922ddab65a3':
  .D........ [ZBX-20232] added changelog entry
  ........S. [ZBX-20232] remove standalone nodes when starting in HA mode and vice versa