Add dpdk_telemetry plugin

stahnma-epel has now migrated to VoxPupuli
name space.

Also in particular the `puppet-epel` version is requirment to
work with CentOS 8.

Require puppet-epel over stahnma-epel

The main differences for CentOS 8 are:
* There is now a new collectd-utils package containing collectdctl
* collectd-python is now a seperate sub package
* python is python3.
* pip command is now pip3
* The rabbitmq plugin no longer works due to lack of python3 support

The python_dir fact will fall back to `/usr/libexec/platform-python`
if `python3` does not exist on the path. This is the python
that collectd is built against and significantly requires.

Note that setting `collectd::ci_package_repo` true will currently
result in yum being configured with a non existant repo since
https://pkg.ci.collectd.org/rpm/ does not exist
for 8.

collectd/collectd-ci#35

Add CentOS 8 support

On some operating systems `collectdctl`, `collectd-nagios`
is contained in a seperate sub package, typically `collectd-utils`

Setting `utils` to `true` will install this sub package if it exists
for an operating system.

New utils parameter to install collectdctl

As of CentOS 8 the write_http is in its own subpackage
so must be installed on CentOS 8.

write_http/disk is own sub package on CentOS 8

* Addition of CentOS 8 support.
* New utils parameter

Release 11.3.0