[kubernetes] disable use_histogram by default (#2542)

conf.d/kubernetes.yaml.example

@@ -7,20 +7,20 @@ instances:
   # The kubernetes check retrieves metrics from cadvisor running under kubelet.
   # By default we will assume we're running under docker and will use the address
   # of the default router to reach the cadvisor api.
-  # 
+  #
   # To override, e.g. in the case of a standalone cadvisor instance, use the following:
   #
   # host: localhost
-  # port: 4194 
+  # port: 4194
   # method: http
  - port: 4194
 
-  # use_histogram controls whether we send detailed metrics, i.e. one per container. 
+  # use_histogram controls whether we send detailed metrics, i.e. one per container.
   # When false, we send detailed metrics corresponding to individual containers, tagging by container id
   # to keep them unique.
   # When true, we aggregate data based on container image.
   #
-   use_histogram: True
+  # use_histogram: True
   #
   # kubelet_port: 10255
   #