Remove hardcoded labels in store shard matcher

[fpetkovski]

Is your proposal related to a problem?

We currently hardcode certain labels in shard matchers because they should not be take account for sharding

thanos/pkg/store/storepb/shard_info.go

Lines 45 to 48 in 67880ca

	// Exclude metric name and le label from sharding
	if lbl.Name == "__name__" || lbl.Name == "le" {
	continue
	}

Describe the solution you'd like

We should completely remove the __name__ label as it should be okay to shard on it.
The le label should be propagated through the query analyzer instead. This will remove coupling on PromQL in Thanos Stores.

Additional context

Slack thread: https://cloud-native.slack.com/archives/CL25937SP/p1661110514624489

[haanhvu]

I'll work on this