internal-client transaction IDs pollute other daemon messages

[Tim Burke]

Running the expirer when there's nothing to in the queue gives me logs like

object-expirer: Starting 731149
swift: - - 30/Apr/2021/19/28/58 HEAD /v1/.expiring_objects%3Fformat%3Djson HTTP/1.0 200 - Swift%20Object%20Expirer - - - - txb27d52a49c4f4695a678f-00608c5a7a - 0.0168 - - 1619810938.850333691 1619810938.867094994 -
object-expirer: Pass completed in 0s; 0 objects expired (txn: txb27d52a49c4f4695a678f-00608c5a7a)
object-expirer: Exited 731149 (txn: txb27d52a49c4f4695a678f-00608c5a7a)

Having a transaction ID logged for the internal-client request is good and proper, but strange for the "Pass completed" and "Exited" messages -- the notion of a "transaction" should have ended as soon as we handed the response back to the caller.

Note that we've previously worked around this in the sharder, but it'd be better-addressed in internal_client itself -- see https://review.opendev.org/c/openstack/swift/+/564488