[container][collectd] Update barometer-collectd container for CentOS 8

[container][collectd] Update barometer-collectd container for CentOS 8

Update collectd to 5.12
Add in CentOS as base for the barometer-collectd container
Remove openstack plugins - they are not used anymore

Use packaged DPDK (v18.11 in CentOS 7 amd v19.11 in CentOS 8)
Install packages from package manager instead of building libpqos,
pmu-tools and librdkafka

Combine install commands into one for CentOS8
(systems/centos/8/build_base_machine.sh)

These changes reduce the size of the container from 1.7GB to ~825MB.

Change-Id: I7e474f9578cdbcc7cce8c4fbc5e297eab89fd371
Signed-off-by: Emma Foley <efoley@redhat.com>