Zabbix

.......... [DEV-2550] added new tests scenarios for event correlation page and refactored old ones

Merge in ZBX/zabbix from feature/DEV-2550-6.0 to release/6.0

* commit 'c01f51f3dbe184fbc730653b7b088ecdf05b743f':
  .......... [DEV-2550] added fixes regarding code review
  .......... [DEV-2550] changed access modifiers
  .......... [DEV-2550] fixed code style
  .......... [DEV-2550] converted testPageEventCorrelation tests to the new framework, added new test scenarios