ARGUS-56: When DB audit log is configured for asynchronous, events are
not flushed to DB until batch-size number of events (100 by default) are
logged.

This condition is only for the first flush to DB. After the first
commit, asynchronous logger flushes to DB at the sooner of the following
conditions:
- batch-size number of events are logged
- max-flush-interval is reached