RHEL setup does not work due to powertools

[jpROC1]

RHEL node setup does not work as power tools does not exist on RHEL.

In the _install.rb file for slurm it detects Centos, alma, rocky and RHEL and then tries to setup the power tools repo however this is no possible on RHEL

[jgregorcmh]

@jpROC1 this was also an issue in the older 2.X templates and exists in 3.X. From our clusters, also running RHEL, perl-Switch package is natively available in RHEL8 from "codeready-builder-for-rhel-8-x86_64-rpms" repo and in RHEL7 from "rhel7-server-optional-rpms". Those repos are already enabled in the images we are using but can be added with subscription manager. I've had to add several switches to our custom code to further handle RHEL versus Centos/Alama/Rocky differences with EPEL.