The AsyncRequestsSender is used extensively both for DDL and for query routing. A lot of places use the request object from the AsyncRequestsSender even if they use something else (like the MultiStatementTransactionRequestsSender) for actually executing the requests.

Now that the dbInfo is using a ShardRef, we can start piping the shardRef through the in memory structures and be able to test that it is working. In this first ticket, we will also need to update the ShardRegistry's getShard to work with shardRef.