errbag/test: wait for the errbag to empty before running new test
errbag/test: wait for the errbag to empty before running new test

TLDR: by the addition of a sleep, the tests now take less time :)

If we don't wait for the channel to be empty before starting the
throttling test, errbag will rightfully throttle 2 times considering we
fill it with more errors than the size of the spanning window.

DevMine/crawld