Zabbix

........S. [ZBX-20951] fixed dependent item discovery validation in LLD

Merge in ZBX/zabbix from feature/ZBX-20951-5.0 to release/5.0

* commit '901155e8a65fb6e63e7ff4f6c4190a49beb26ef7':
  ........S. [ZBX-20951] reverted dependent item validation without recursion
  ........S. [ZBX-20951] removed redundant dependent item validation
  ........S. [ZBX-20951] added recursive dependent item discovery validation to correctly work with multiple levels of nesting
  ........S. [ZBX-20951] removed redundant NULL check
  .D........ [ZBX-20951] added changelog entry
  ........S. [ZBX-20951] fixed validation of LLD dependent items