We can use OpMsgRequestBuilder::create() rather than OpMsgRequest::fromDBAndBody when creating the opMsg request in SEPTransactionClient::runCommand - otherwise we may include the wrong serialized version of database name in the op msg request (we may include a prefix even when we're setting $tenant here). It works now because we always pass the non-prefixed db name to SEPTransactionClient::runCommand in this file by calling .db() on the DatabaseName.

Change SEPTransactionClient::runCommand to use a DatabaseName instead of a StringData and internally call OpMsgRequestBuilder::create instead of OpMsgRequest::fromDBAndBody.