Rebase of `null_eq_null_data_migration` onto `msrun_loader` (ignore)

[hepcat72]

Summary Change Description

I wanted to create a PR for my rewrite of the null_eq_null_data_migration branch (PR #953), but after the rebase, there are changes in the diff that relate to the ones in the branch that null_eq_null_data_migration branched off of that were approved in #949. So that those don't show up in the rewrite of #953's code (the migration files) in this PR, I created a branch that only contains the rebase commit. I intend to merge the PR of the migration change (for #963) into this branch before merging into main.

I rebased off #962 (msrun_loader) because it has required changes for the next step: uncommenting the clean code that prevents the issues that this data migration fixes) from happening again.

Affected Issues/Pull Requests

• Resolves no issue. It is a rebase of #953 onto the branch for #962.

Review Notes

See comments in-line.

Checklist

This pull request will be merged once the following requirements are met. The author and/or reviewers should uncheck any unmet requirements:

• Review requirements
  • Minimum approvals: 1
  • No changes requested
  • All blocking issues resolved by reviewers
  • Specific reviewers: @add_username_here
  • Review period: 2 days
• Associated issue/pull request requirements:
  • [x] All requirements in affected issues marked "resolved" are satisfied
  • [x] All required pull requests are merged (or none)
• Basic requirements
  • [x] All linters pass
  • [x] All tests pass
  • [x] All conflicts resolved
• Overhead requirements
  • [x] New/changed method tests implemented/updated (or no change)
  • [ ] Updated Unreleased section of changelog.md (or no change)
  • [x] Migrations created & committed (or no change)

[hepcat72]

After a rebase and a merge, this PR is no longer needed. It was just here to make the diff only show new changes in another PR anyway.