Zabbix

A.F.....S. [ZBXNEXT-6250] added option to opt-out of "escalation canceled" messages

* commit '26dcc0b43620fc086bef92acbf4d73166f8f1684':
  ..F....... [ZBXNEXT-6250] minor code refactoring
  .......... [ZBXNEXT-6250] added new notify_if_canceled field to data.tmpl
  ........S. [ZBXNEXT-6250] removed redundant blank line
  .......... [ZBXNEXT-6250] typo fix
  .......... [ZBXNEXT-6250] typo fix
  .......... [ZBXNEXT-6250] updated integration tests
  ........S. [ZBXNEXT-6250] changed log message string (AmE)
  .D........ [ZBXNEXT-6250] fixed changelog
  ADF....... [ZBXNEXT-6250] implemented escallation cancellation frontend and API part
  ........S. [ZBX-20177] updated constant names (server part)
  ........S. [ZBXNEXT-6250] changed field name
  ........S. [ZBXNEXT-6250] initial commit