Merge pre|post puppet resources into pre|post config.

Merge pre|post puppet resources into pre|post config.

The [Pre|Post]Puppet resources were renamed in
https://review.openstack.org/#/c/365763.
This was intended for having a pre/post deployment
steps using an agnostic name instead of
being attached to a technology.

The renaming was unintentionally reverted in
https://review.openstack.org/#/c/393644/ and
https://review.openstack.org/#/c/434451.

This submission merge both resources into one,
and remove the old pre|post hooks.

Closes-bug: #1669756
Change-Id: Ic9d97f172efd2db74255363679b60f1d2dc4e064