Stop roscore using killall before ending the validate script

builder/image-validate.sh

@@ -37,7 +37,7 @@ apt-cache show openvpn
 # sudo -E sh -c 'apt-get install -y debian-goodies'
 # dpigs -H -n 100
 
+killall roscore
+
 echo "Move /etc/ld.so.preload back to its original position"
 mv /etc/ld.so.preload.disabled-for-build /etc/ld.so.preload
-
-sleep 10