Move CI to c6a single node

[climbfuji]

Description

Rename .github/workflows/run_ec2_pcluster.yaml to .github/workflows/ubuntu-c…i-x86_64.yaml and update to run on AWS EC2 single node instance c6a.8xlarge. Since the latter uses tcl/tk environment modules instead of lua/lmod modules, an update is required for the setup script for the UFS c48 data in fv3-jedi so that it works for both tcl/tk and lua/lmod (tested in CI with tcl/tk, and on my macOS with lua/lmod).

Temporary branch name change for fv3-jedi needs to be reverted after https://github.com/JCSDA-internal/fv3-jedi/pull/1196 is merged.

Issue(s) addressed

Last PRs needed to switch ufs-bundle CI runner to new instance.

Dependencies

• waiting on https://github.com/JCSDA-internal/fv3-jedi/pull/1196

Impact

n/a

Checklist

• I have performed a self-review of my own code
• I have made corresponding changes to the documentation
• I have run the unit tests before creating the PR

[climbfuji]

This is ready for review and merging

[ashley314]

Thanks!