Waiting 5 seconds until the pending file queue has been processed slows
down the tests significantly, instead of waiting for the time to pass
inject events with appropriate timestamps, the real timer events are
filtered out. This shortens the runtime from 7.6 to 2.6 seconds.
The first test still uses real timers, to check if the chained triggering
of the timers from the slots work.
Depends on D21792