fix: check if we can remove the time.Sleep to wait the plugin load

[Pantani]

          It seems that adding the `KillClient` call might make the `time.Sleep` call redundant 🤔, so it might be possible to remove the `time.Sleep`. Killing the client should try to stop it gracefully, so buffers should be flushed properly if the plugin client is running without issues.

Maybe you could add a TODO? If it can't be properly tested to be sure in fact the time.Sleep is redundant now.

Originally posted by @jeronimoalbi in #4091 (comment)