Fix race in Query Log Test (#6727)
Fix race in Query Log Test (#6727)

A data race can happen if we run t.Log after the test t is done -- which
in this case is highly possible because of the use of subtests and the
fact that we call t.Log in a goroutine.

Signed-off-by: Julien Pivotto <df1ed88a312a603dfee9f157a90fa8f7f195ab59@inuits.eu>
GoogleCloudPlatform/prometheus,alileza/prometheus,keegancsmith/prometheus,keegancsmith/prometheus,keegancsmith/prometheus,Gouthamve/prometheus,keegancsmith/prometheus,kangwoo/prometheus,kangwoo/prometheus,Gouthamve/prometheus,kangwoo/prometheus,prometheus/prometheus,alileza/prometheus,prometheus/prometheus,GoogleCloudPlatform/prometheus,alileza/prometheus,keegancsmith/prometheus,kangwoo/prometheus,Gouthamve/prometheus,alileza/prometheus,alileza/prometheus,prometheus/prometheus,prometheus/prometheus,Gouthamve/prometheus,prometheus/prometheus,GoogleCloudPlatform/prometheus,GoogleCloudPlatform/prometheus,GoogleCloudPlatform/prometheus