Fix event_handler coverage test by changing timeout.

[wen-coding]

Problem

The original event_handler tests were reverted because they failed coverage tests on ci machine.

Summary of Changes

• We can directly call handle_event, but that won't work in the future if we somehow add some code outside handle_event, blindly testing input/output on the event loop is still ideal because it is ignorant of internal implementation
• When I did revert of 8243 (Revert "votor: ignore event_handler tests (#8243)" agave#8251), I set the timeout to 50ms and the test passed. To be extra careful, I'm setting the timeout to 100ms now, and I'll test it on ci machine for a few days ((Draft) Draft to try test strategy, do not review please. agave#8304) to see that coverage tests keep passing
• Also reworked a few delay related items to make sure we don't actually wait that long in tests