jenkins/macros: rm /etc/default/puppet when removing puppet

When uninstalling puppet on Ubuntu platform, we need to remove
/etc/default/puppet because when re-installing puppet4 on Xenial,
package will fail to finish installation since this file already exist.

Change-Id: Ic2280bdefa25126eaa35412e36dd8d1643ef1254

jenkins/jobs/macros.yaml

@@ -323,6 +323,9 @@
               sudo apt-get remove -y --purge facter puppet puppet-common hiera
               sudo apt-get update
               sudo apt-get install -y libxml2-dev libxslt-dev zlib1g-dev
+              # /etc/default/puppet is not purged when removing Puppet
+              # but need to be dropped if we want to re-install puppet-agent on Xenial
+              sudo rm -rf /etc/default/puppet
           fi
 
 - builder: