Zabbix

........S. [ZBX-19961] fixed possible crash when trying to access trigger that was removed from cache

Merge in ZBX/zabbix from feature/ZBX-19961-5.4-2 to release/5.4

* commit '13688bf7b01f380ca4a1ed4145c27347eec83b07':
  .D........ [ZBX-19961] changed changelog entry location
  ........S. [ZBX-19961] fixed trigger sync
  ........S. [ZBX-19961] converted trigger itemids merging function to appending
  ........S. [ZBX-19961] fixed shared memory leak when removing trigger
  ........S. [ZBX-19961] fixed triger->itemids list merge
  ........S. [ZBX-19961] fixed item-trigger update when removing triggers