HUE-8993 [core] Avoid hardcoding an hdfs cluster in the image

If set in the base image, it can't be overriden later as there is no
way to clear an ini section.

tools/container/hue/hueconf/hue.ini

@@ -46,7 +46,5 @@ backend=desktop.auth.backend.AllowFirstUserDjangoBackend
 [libzookeeper]
 [hadoop]
 [[hdfs_clusters]]
-[[[default]]]
-fs_defaultfs=hdfs://localhost:8020
-webhdfs_url=http://localhost:20101/webhdfs/v1
+[[yarn_clusters]]
 [beeswax]