Retryable internal transaction remove sessions before expirations if the txnNumber passes a threshold 

The test assumes to begin with no open sessions, and verifies the mentioned logic will be applied after passing a limit specifically lowered by the test sessions.

After SERVER-81190 unsharded collection are tracked using the createCollectionCoordinator, the implicit creation at the beginning makes the test failing due to the extra session opened (and not yet expired) during the creation process.

The goal of this ticket is to re-write/adapt the test knowing this session is now present.