Currently, retrieving documents from a time-series collection using the find command and an index spec as a hint returns a BadValue exception as the index spec in the hint isn't translated to its corresponding buckets collection index spec. We currently only support indexes on the timeField and metaField for time-series collections, so we should allow queries with index spec as hints to work by translating the index spec in the hint to its buckets collection index spec. This helper function will be useful as it performs the index spec translation.