Use Rocky instead of CentOS for push button clusters

Fixes #672 (closed) Fixes #665 (closed)

This relies on the rocky-linux branch of the CRI_Jetstream_Cluster repo. Once/if that is merged to the main branch in we should change the branch in Helpers.Helpers.createClusterYaml accordingly.

Other changes introduced:

• Pipe output from cluster_create_local.sh to local_create.log
• Keep Docker installed on head node by passing -d to cluster_create_local.sh. This fixes problem where Guacamole did not work on the head node.

How to Test

• Follow these steps and ensure you see the right output in nodes_2.out
  • Note, you'll have to run the sbatch command as the rocky user, so for now run sudo su - rocky after SSH-ing into the head node. I will make a PR to the docs to address this.
• Also ensure that web shell works on the head node

Screenshots

(If visual changes are introduced, show what they look like)

QA Checklist

• Any changes to 'widgets' in src/Style/Widgets/? If so:
  • Update src/Style/StyleGuide.elm showing example usage of that widget
• Were any app flags created, modified, or removed? If so:
  • Update config.js and all files in environment-configs/, including docker-config.js
  • Update "Runtime configuration options" documentation in README.md

Post-Merge Checklist

• Create follow-up issues for anything left over for another merge request
  • If any technical debt is introduced, assign these follow-up issues to the MR submitter