Series metadata queries are not making it to ingesters for older time ranges

[joe-elliott]

These lines:

cortex/pkg/querier/distributor_queryable.go

Lines 91 to 104 in a4aad5d

	if q.queryIngestersWithin > 0 {
	now := time.Now()
	origMinT := minT
	minT = util.Max64(minT, util.TimeToMillis(now.Add(-q.queryIngestersWithin)))
	if origMinT != minT {
	level.Debug(log).Log("msg", "the min time of the query to ingesters has been manipulated", "original", origMinT, "updated", minT)
	}
	if minT > maxT {
	level.Debug(log).Log("msg", "empty query time range after min time manipulation")
	return storage.EmptySeriesSet()
	}
	}

From this PR:
#2904

are currently preventing metadata queries from correctly hitting the ingesters in chunk storage. If a metadata query has a time range from before the ingesters it should still be passed in. Ingesters ignore ranges for metadata queries so it's ok to pass older time ranges to them.

https://github.com/cortexproject/cortex/blob/master/pkg/ingester/ingester.go#L833-L837

cc @gouthamve