SERVER-72146 added extra statistics related to migration, we could use it to log it at the end of the operation to give more information about the current state of migrations, specifically the throughput, and how long a migration is taking.

Specifically, at the end of a successful migration we should log:

• migrationId: to identify the migration
• totalTimeMillis: to know the total amount of time taken by the migrations in milliseconds
• docsCloned: the number of documents cloned to the recipient shard by the migration
• bytesCloned: the total number of bytes cloned to the recipient shard by the migration
• cloneTime: the final amount of time taken by the clone phase by the migration in milliseconds.