Use direct mount for puppet docker container

Relies on https://review.openstack.org/#/c/107314/

Removing workaround for mount of /etc/puppet
to /puppet, then ln -s /puppet/{files} into
/etc/puppet, because it breaks upgrade schema
where /etc/puppet/$VER is added.

Change-Id: I31470af079bc88ae4303dc511bfe2b1c1c9c2fed
Partial-Bug: #1339688
(cherry picked from commit 8b658b11be66afea92acbe362064aa5ee41de22a)
Merge "Use direct mount for puppet docker container" into stable/5.0