Achieve metrics coverage on stores

[blakehatch]

The stores that are missing metrics are:

• [x] Completeness Checking Store
• [ ] Dedup Store
• [ ] Grpc Store
• [ ] Noop Store
• [ ] Ref Store
• [ ] S3 Store
• [x] Size Partitioning store

[aaronmondal]

Not saying I'm against implementing it in the current infra, but I want to mention that this could be a waste of time to implement in our current setup. If we do this now we'll need to port all those metrics over to the otel-subscriber later. If we migrate to otel-subscriber first and change the log, error, info etc messages to the more idiomatic instrumentation syntax we get all these metrics for free.

[blakehatch]

Oh wow I actually didn't know otel gives us metrics through logging that's really nice. Will leave this here for now as a reference for which stores have metrics currently for cloud and which don't then we can close this issue along with the otel migration.

[MarcusSorealheis]

Is this still an issue? Cc @blakehatch