Address skipped tests

[jazairi]

Why these changes are being introduced:

The codebase has several skipped tests, some of
which have been skipped for years. We should
reevaluate whether these tests still need to be
skipped, or if they're even still necessary.

Relevant ticket(s):

• ETD-701

How this addresses that need:

• Fixes admin advisor tests related to processor
  authorization. The underlying issue was that the
  Ability model did not provide the necessary
  permissions for the processor role to perform
  the specified tasks.
• Implements Preservation Submission Job test
  confirming behavior when a 400 error is returned
  using a stubbed response.
• Removes thesis integration test asserting that
  the thesis form fails validation without files.
  This validation does not exists, nor should it,
  as files are added separately in the transfer
  workflow.
• Fixes admin integration test that fails only in
  GitHub Actions CI. This was likely due to a race
  condition and has been resolved by targeting
  a specific fixture, rather than calling
  ThesisDepartments.first
• Does not alter a test that is skipped because
  it is slow to run. Because this skip is
  performance-related and provides an optional
  override, it makes sense to leave it in place.

Side effects of this change:

• The Ability model as a whole may require an
  overhaul. The processor role is not currently
  in use, and it may not be needed.

Developer

Accessibility

• ANDI or WAVE has been run in accordance to our guide.
• This PR contains no changes to the view layer.
• New issues flagged by ANDI or WAVE have been resolved.
• New issues flagged by ANDI or WAVE have been ticketed (link in the Pull Request details above).
• No new accessibility issues have been flagged.

New ENV

• All new ENV is documented in README.
• All new ENV has been added to Heroku Pipeline, Staging and Prod.
• ENV has not changed.

Approval beyond code review

• UXWS/stakeholder approval has been confirmed.
• UXWS/stakeholder review will be completed retroactively.
• UXWS/stakeholder review is not needed.

Additional context needed to review

Test suite should pass locally and in CI.

Code Reviewer

Code

• I have confirmed that the code works as intended.
• Any CodeClimate issues have been fixed or confirmed as
  added technical debt.

Documentation

• The commit message is clear and follows our guidelines
  (not just this pull request message).
• The documentation has been updated or is unnecessary.
• New dependencies are appropriate or there were no changes.

Testing

• There are appropriate tests covering any new functionality.
• No additional test coverage is required.

[coveralls]

coverage: 98.288% (+0.002%) from 98.286% — etd-701 into main