Remove unused Events and fix _wait_for_worker_startup behavior

[reggie-firework]

When trying to use TaskIQ for distributing slow-to-start processes (due to AI imports) meant for long-running tasks, we kept running into issues where TaskIQ would start our worker subprocesses from ProcessManager and then within 10-15 seconds would erroneously deem them "not alive" and restart them. After some experimentation with a forked repo we discovered that this was because the _wait_for_worker_startup was not properly waiting for our python process to report alive.

This PR fixes that method and removes the unused Events and imports, which from what I could tell were never being signaled from anywhere anyways. I tested a simplified version of this change on our dev system, so it seems like this should work, but after cleaning up this change I have not retested other than running unit tests. We are likely going to switch to Celery for observability benefits, but I figured giving you folks this PR would be the right thing to do for our OpenSource community :)

[s3rius]

This event was used by previous versions of taskiq, where we were setting this even after broker startup.

Although, since they were removed, I guess it's safe to remove events from process manager as well, as you have suggested.

Also, in regards to observability, what do you miss? Have you tried https://github.com/taskiq-python/taskiq-admin?

[reggie-firework]

This event was used by previous versions of taskiq, where we were setting this even after broker startup.

Although, since they were removed, I guess it's safe to remove events from process manager as well, as you have suggested.

Also, in regards to observability, what do you miss? Have you tried https://github.com/taskiq-python/taskiq-admin?

Thank you for sharing this, this looks promising! We did not find this in our initial search for observability. We will investigate this further. I think what our company is most interested in in terms of observability is the ability to hook up to lots of worker-state related events (started, ended, failed, idle, busy, process cpu, process memory, etc)