Remove prepare-node element

This element is no longer used. jenkins/cache/files is now a symlink
and jenkins/cache/pip no longer seems used.

Change-Id: I558b3bff7da97853d53ab5ef71b0a9854238e592
Signed-off-by: Paul Belanger <pabelanger@redhat.com>

nodepool/elements/openstack-repos/element-deps

@@ -1,3 +1,2 @@
 cache-url
-prepare-node
 source-repositories

nodepool/elements/prepare-node/README.rst

@@ -1 +0,0 @@
-Prepare the node

nodepool/elements/prepare-node/element-deps

@@ -1 +0,0 @@
-nodepool-base

nodepool/elements/prepare-node/install.d/20-prepare-node

@@ -1,25 +0,0 @@
-#!/bin/bash
-# Copyright (C) 2011-2013 OpenStack Foundation
-#
-# Licensed under the Apache License, Version 2.0 (the "License");
-# you may not use this file except in compliance with the License.
-# You may obtain a copy of the License at
-#
-#    http://www.apache.org/licenses/LICENSE-2.0
-#
-# Unless required by applicable law or agreed to in writing, software
-# distributed under the License is distributed on an "AS IS" BASIS,
-# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
-# implied.
-#
-# See the License for the specific language governing permissions and
-# limitations under the License.
-
-# dib-lint: disable=setu setpipefail
-if [ ${DIB_DEBUG_TRACE:-0} -gt 0 ]; then
-    set -x
-fi
-set -e
-
-mkdir -p ~jenkins/cache/files
-mkdir -p ~jenkins/cache/pip