Fix flake in TestMultiVA (#6141)
Fix flake in TestMultiVA (#6141)

Fix a race condition in one of the TestMultiVA test cases.

There are many other possible flakes in these tests, because
they use real HTTP to talk to a fake remote VA on localhost,
but we can at least trivially remove this race condition.

Fixes #6119
letsencrypt/boulder,letsencrypt/boulder,letsencrypt/boulder