'progname' is actually only fullfilled for Openstack services logs.
They are missing for MariaDB and RabbitMQ logs.
When using Kibana, "progname" field appears empty, hence it's difficult
to known where logs comes from.

Change-Id: Ifcbfd981a34a8d64ea69d37934c7f0fae10a90b5
Closes-Bug: #1713412