7c5a0b06a4
This should make the test more robust, considering the strange hang in https://hydra.nixos.org/build/267517233/nixlog/8 `builder` seems to have reached `multi-user.target` before the SSH connection was established, but this seems to be coincidental. This does tell us that enforcing this has a minimal cost in terms of runtime. Waiting for `multi-user.target` on the client is honestly paranoid, but flaky tests are very bad for productivity.