Merge branch 'jgfouca/update_cime_subm_2024_03_20' into next (PR #6303)

... to 4388509869bd5988d6315e2da65b1a2fbfa604fa

Changes:
1) Initialize machine to None
2) Add option to ignore diffs across the system (useful for perf testing)
3) case.submit: Always try to download input data (avoid DL data on compute node if possible)

Fixes:
1) Update cprnc submodule. Contains some cmake fixes
2) Points the TSC and PGN tests to updated input data for E3SMv3
3) Fixes testing workflow for prs from forked repos.

[BFB]

* jgfouca/update_cime_subm_2024_03_20:
  Update CIME submodule