Remove some unreliable tests

Logrus buffers its output internally, which makes these tests fail intermittently. They're also not a good example to follow generally.

We now have acceptance tests that exercise this functionality so I'm pretty relaxed about losing the expectations. However, we can test them by inspecting the server-received metadata too, so there's no loss of coverage here.

The move from logrus to labkit for logging also makes these tests hard to justify keeping.

Closes #477 (closed)