Simplify sharding logic

[rfratto]

PR Description

This PR simplifies the scraping service sharding mechanism by removing the scraping service manager and performing ownership checking locally directly in the shard logic.

This removes the need for a ton of code.

Which issue(s) this PR fixes

Notes to the Reviewer

Previously hashing was used to cache whether an instance needed to be updated and ignoring the ApplyConfig if it didn't. This hasn't been necessary for a while; ApplyConfig for an unmodified instance is a no-op.

PR Checklist

(Internal change, no changelog or documentation)

• CHANGELOG updated
• Documentation added
• Tests updated

[mattdurham]

To restate the above and the code is basically no need to check if it changed just apply it unilaterally?

[rfratto]

To restate the above and the code is basically no need to check if it changed just apply it unilaterally?

Yeah, it was added way back when re-applying a config always restarted the underlying instance. That changed in #145 but the logic here was never removed.

[rfratto]

🤔 I added a test to make sure the sharding is working but the k3d example still has every node sharding all configs to themselves. I need to look into this more.

[rfratto]

🤔 I added a test to make sure the sharding is working but the k3d example still has every node sharding all configs to themselves. I need to look into this more.

Found the bug, I forgot to update watchKV. There should be a test for this.