Zabbix

.......PS. [DEV-4404] made initialization of read-only js environment for preprocessing and zabbix_js

Merge in ZBX/zabbix from feature/DEV-4404-7.0 to release/7.0

* commit '94cfedc70f76151024a00533d1891a87bb16da35':
  .......PS. [DEV-4404] removed redundunt initialization
  .......PS. [DEV-4404] removed empty lines
  .......PS. [DEV-4404] made initialization of read-only js environment for preprocessing and zabbix_js
  .......PS. [DEV-4404] defined ZBX_ES_DEFPROP_READONLY
  .......PS. [DEV-4404] made as RO any custom functions
  .......PS. [DEV-4404] made Zabbix.log & Zabbix.sleep as RO, removed persistent js context from alerter
  .......PS. [DEV-4404] removed persistent js context for script items

(cherry picked from commit 84e8eab6a73133e3ad45ea2b7618d6be321b2894)