SERVER-71612 introduced a catalog manager method merging in one-shot contiguous sequences of chunks for a given collection for a given shard.

Purpose of this ticket is to enhance that method in order to take into account the onCurrentShardSince field introduced by SERVER-71615 and the jumbo flag.

Two or more contiguous non-jumbo chunks belonging to the same collection are going to be considered mergeable when they are owned by the same shard and their history can be safely purged without breaking transactions and snapshot reads.

Technically, this means that each chunk to merge is required to fulfill the following conditions:

• Has never been migrated.
  OR
• The last migration involving it has happened more than minSnapshotHistoryWindowInSeconds ago AND more than transactionLifetimeLimitSeconds (NB: let's be consistent with this windowInSeconds).