
Update `ZipkinHttpClientSenderTests` to use one mock server per test rather than a shared static. For some reason the mock server sometimes seems to get itself in a deadlock state which causes the client to fail with a `HttpTimeoutException`.
Update `ZipkinHttpClientSenderTests` to use one mock server per test rather than a shared static. For some reason the mock server sometimes seems to get itself in a deadlock state which causes the client to fail with a `HttpTimeoutException`.