test/min-timeout-wait: tweak max allowed time when having events

It really should not wait at all, but if we allow 100ms of wait,
then a bit of slack outside of 1ms is fine. This can happen on UP
systems where we get preempted, for example. Assume up to 5msec
is totally fine.

Signed-off-by: Jens Axboe <axboe@kernel.dk>