kuberentes: roll back recent Kubernetes client changes
kuberentes: roll back recent Kubernetes client changes

https://golang.org/cl/21765 was not tested and not adequately reviewed
and doesn't work at all. Roll it back for now, since the blind fix in
https://golang.org/cl/21765 helped a bit but wasn't enough.

Change-Id: I781fac04d019fa5e6120ec398e13671b89d802c5
Reviewed-on: https://go-review.googlesource.com/25043
Reviewed-by: Johan Euphrosine <aeff70c2aef2cec1cd2754756b5d3e6402001c31@google.com>
Reviewed-by: Brad Fitzpatrick <ae9783c0b0efc69cd85ab025ddd17aa44cdc4aa5@golang.org>

golang/build,golang/build,golang/build,golang/build