Remove dead code from cleanup-host.sh script

sourcing validate-docker-execute.sh script is not needed anymore and
should be removed.

Change-Id: Ie40ddcd36e71337d94f49467bfb0f8aae50353f7

tools/cleanup-host

 #!/bin/bash
 
-# Move to top level directory
-REAL_PATH=$(python -c "import os,sys;print os.path.realpath('$0')")
-cd "$(dirname "$REAL_PATH")/.."
-. tools/validate-docker-execute.sh
-
 # Spawning the neutron agents containers leaves artifacts on the host.
 # This script removes these artifacts.
 ip netns list | while read -r line ; do
@@ -57,4 +52,3 @@ for dir in $FOLDER_PATH*; do
         rm -rfv $dir
     fi
 done
-