Zabbix

.......PS. [ZBX-21430] fixed item scheduling when host proxy assignment changes or host is re-enabled

Merge in ZBX/zabbix from feature/ZBX-21430-6.2 to release/6.2

* commit 'fb5be7b1205730665fe90e2b94381a4b975b1eaf':
  .......... [ZBX-21430] fixed comments and changelog entry
  .......PS. [ZBX-21430] style fix
  .D........ [ZBX-21430] added changelog entry
  .......PS. [ZBX-21430] replaced vector with hashset for activated host lookups
  .......PS. [ZBX-21430] removed unnecesary check for first sync
  .......PS. [ZBX-21430] fixed item rescheduling after host monitoring is restarted
  ........S. [ZBX-21430] fixed item being polled once by server after host is assigned to proxy and configuration cache has been reloaded