Zabbix

........S. [ZBX-20139] renamed ExternalAddress to NodeAddress and removed ListenIP/Port dependency

Merge in ZBX/zabbix from feature/ZBX-20139-5.5 to master

* commit '26dc2d194b42e76ab78ce48ff80c1a1eb7856195':
  ....I..... [ZBX-20139] updated zabbix server conf file
  ........S. [ZBX-20139] updated NodeAddress validation to block empty IP/hostname
  .D........ [ZBX-20139] improved NodeAddress description
  ........S. [ZBX-20139] fixed validation of NodeAddress
  ....I..... [ZBX-20139] updated server configuration file
  ....I..... [ZBX-20139] updated default server configuration file
  .D........ [ZBX-20139] added changelog entry
  ........S. [ZBX-20139] Renamed ExternalAddress to NodeAddress and removed ListenIP/Port dependency