It can happen for a shard to own several contiguous sequences of chunks for a given collection. In order to merge them, issuing single merge requests will result in bumping several times the shard version causing frequent routing table refreshes.

Purpose of this ticket is to implement a mergeAllChunksOnShard method on the sharding catalog manager that will take care of squashing at once all "mergeable" chunks a shard owns for a given collection and bump the shard versions accordingly. All of that needs to happen in a single transaction.