Zabbix

..F....... [ZBX-20854] fixed missing headers in Columns field in Top hosts widget configuration form

Merge in ZBX/zabbix from feature/ZBX-20854-6.0 to release/6.0

* commit 'bd5b80658728e289527c291b4f03c6e0564117e9':
  ..F....... [ZBX-20965] removed CRowHeader class
  ..F....... [ZBX-20854] fixed missing headers in Columns field in Top hosts widget configuration form