Short-circuit chunk dedup in proxy (thanos-io#5816)

The store proxy deduplicates series by calculating a hash on the each
aggregate chunk. If at least one hash is not present in the dedup-map,
the entire series chunk is added to the response, including all aggregate
chunks.

Because of this, we can short-circuit deduping chunks and stop early if any
aggregate chunks is not previously seen.

Signed-off-by: Filip Petkovski <filip.petkovsky@gmail.com>

Signed-off-by: Filip Petkovski <filip.petkovsky@gmail.com>

pkg/store/proxy_heap.go

@@ -139,6 +139,7 @@ func (d *dedupResponseHeap) At() *storepb.SeriesResponse {
 				if _, ok := chunkDedupMap[hash]; !ok {
 					chk := chk
 					chunkDedupMap[hash] = &chk
+					break
 				}
 			}
 		}