Zabbix

........S. [ZBXNEXT-3877] Simplified the logic for sending trends

The disable_from field is used only if weare using the zabbix database as an
optimization for recognizing which records to insert and which to update.
In the case of an history service, this optimization must be performed by the
service itself and it will be completely implementation-defined.
Also, fixed the name of dc_update_trends_cache() with dc_set_cache_disable_from(),
because there is no logic there involving the history service behavior and it's
only meant for optimizing subsequent syncs with the zabbix database..

From Andris Zeila