Zabbix

.......PS. [DEV-4407] simplified value preprocessing request to reduce allocations

Merge in ZBX/zabbix from feature/DEV-4407-7.5 to master

* commit '65b1c88f85cfba77b8ba0417c02e4c99d46e6d46':
  .......PS. [DEV-4407] fixed cached message size calcualtions when sending data to preprocesing
  .......PS. [DEV-4407] fixed preprocessing message caching over 2G
  .......PS. [DEV-4407] fixed indentation
  .......PS. [DEV-4407] removed unused structure field
  .......PS. [DEV-4407] restored total cached message size check when sending data to preprocessing. Also restored cached meassage cleanup after flush.
  .......PS. [DEV-4407] removed redundant assignments
  .......PS. [DEV-4407] fixed log value type pushing to preprocessing
  .......PS. [DEV-4407] simplified preprocessing IPC request