Zabbix

........S. [ZBXNEXT-1675] reworked housekeeper:
  - converted global housekeeping settings into seconds;
  - added support for time units in global housekeeping settings;
  - added support for user macros and time units in item history and trends storage settings from housekeeper perspective;
  - fixed inability to globally override item history and trend storage if internal housekeeping is not enabled.