Feature/issue 81 rm files

[michelleharrold]

Pull Request Testing

• [ ] Describe testing already performed for these changes:
  All three cases (sandy, snow, and derecho) were run end-to-end on a Mac (only Docker commands, no Singularity); this included building the Docker images from scratch.

This PR address four changes: 1) Removes unnecessary files that have been lingering around the repo. (Issue #81) 2) The container-dtc-nwp/components/scripts/common/pull_nomads_gfs.ksh contained broken links; script was updated to work. 3) METviewer YML files were updated to v4.0 -- this is assuming this will be the last PR before the v4.0 release! 4) Python plots broke with the upgrade to matplotlib 3.5.1 from v3.3.4. A number of fixes were made to address this. (Issue #82)

• [ ] Recommend testing for the reviewer(s) to perform:
  @jwolff-ncar, @fossell, and @mkavulich - perhaps we can talk about divvying up testing in our upcoming meeting and update accordingly.

• [ ] Are any changes to the online tutorial required for this PR? [No]
  

• [ ] Will this PR change the output of any of the existing cases? [No]
  

• [ ] Please complete this pull request review by [ASAP].
  

Pull Request Checklist

• [ ] Ensure the PR title matches the feature or bugfix branch name.
• [ ] Define the PR metadata, as permissions allow: Select: Reviewer(s), Projects(s), and Milestone.
• [ ] After submitting the PR, select Linked issues with the original issue number.
• [ ] After the PR is approved, merge your changes, as permissions allow.
• [ ] Close the linked issue and delete your feature or bugfix branch from GitHub.