Testing images for slurm, pbs, and hadoop, are no longer buildable

[consideRatio]

When trying to rebuild the docker images used to test pbs/slurm/hadoop, the base image can't rebuild because of...

 => ERROR [3/7] RUN yum install -y         sudo         git  && yum clean all  && rm -rf /var/cache/yum                                                        0.5s
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 > [3/7] RUN yum install -y         sudo         git  && yum clean all  && rm -rf /var/cache/yum:                                                                   
0.271 Loaded plugins: fastestmirror, ovl
0.430 Determining fastest mirrors
0.459 Could not retrieve mirrorlist http://mirrorlist.centos.org/?release=7&arch=x86_64&repo=os&infra=container error was
0.459 14: curl#6 - "Could not resolve host: mirrorlist.centos.org; Unknown error"

If we can migrate to debian or ubuntu for example, that would be great - but this image is the base image for three kinds of situations (slurm, openpbs, hadoop), so it can be tricky to do this.