mantle/kola: drop reference in comment

The config was updated in 3c74005 to add steady_interval_secs but
in reality it's more convenient for us to just start zincati here
anyway. Let's drop the instructions to update, since we're just
planning on keeping this here now anyway.

mantle/kola/tests/upgrade/basic.go

@@ -321,7 +321,7 @@ func runFnAndWaitForRebootIntoVersion(c cluster.TestCluster, m platform.Machine,
 
 func waitForUpgradeToVersion(c cluster.TestCluster, m platform.Machine, version string) {
  runFnAndWaitForRebootIntoVersion(c, m, version, func() {
- // XXX: update to use https://github.com/coreos/zincati/issues/203
+ // Start Zincati so it will apply the update
  c.RunCmdSync(m, "sudo systemctl start zincati.service")
  })
 }