Consider bringing back deduplication check; per store type.

[bwplotka]

This removes deduplicate check we had as there was a bug there: #1636

Ideally, we want to bring this back, but with more advanced logic: e.g per component there should be no duplicate, but also Querier vs others should not duplicate (as Querier is just a proxy in StoreAPI mode)

Goals:

• To notify user early about misconfiguration. Essentially it does not make sense and it will pollute the system (compactor will halt) if two Prometheus-es has same data.
• Pointing to the same StoreAPI is inefficient.
• Pointing to the StoreAPIs with same data (e.g 2 StoreGW operating on the same bucket) is inefficient

Notify user, and block all but one of the duplicates.

We consider flag to opt-out from this check.

[bwplotka]

This is no go as to do it right, we would need to check duplicates for certain time ranges. Plus all works fine if you duplicate except write path which we don't really touch in Querier.

I think it's fine to just keep Querier without any check. This adds warning for the single case of Ruler or Sidecar having same external labels which is not ideal.

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.