Convert Int/Pack jobs to use baseline Ubuntu/CentOS images

We are currently using a pretty generic Java builder VM image for most Int/Pack jobs. Ideally we'd have an image or set of images more customized for our needs. Should start with a vanilla VM image and customize it ourselves for now, maybe bake our config into a Packer build later.

Some basic images were added by abelur:

https://git.opendaylight.org/gerrit/gitweb?p=releng/builder.git;a=blob;f=jjb/releng-jobs.yaml;h=caf99a049504cbff695f77928976d7bfd766de8e;hb=refs/heads/master#l93

But trying to convert the nodes in the sandbox (on 2017/10//10), I get errors like

> There are no nodes with the label ‘centos7-baseline-2c-4g’

So I guess images hadn't actually been built/pushed? Should retest and follow up with helpdesk if there's still a problem.

Imported from Trello