Syntax to be consistent across docTimer and cronTimer

Current Syntax:
cronTimer(func_callback, payload_context, timestamp);
docTimer(func_callback, doc_id, timestamp);

Change to below to make them consistent:
cronTimer(func_callback, timestamp, payload_context);
docTimer(func_callback, timestamp, doc_id);

Also see MB-29075 to make docTimers accept payloads.