Explicitly waiting for influxdb2 in the test, instead of fixing the
underlying issue[1], was hiding a real bug[2]. Now that the bug has been
fixed we can remove the wait code.
[1] Commit 732d36522f ("nixos/influxdb2: wait until service is ready")
[2] https://github.com/NixOS/nixpkgs/issues/317017 ("Scrutiny tries to start before influxdb has started")