IQSS/8028 enable import with test dois

[qqmyers]

What this PR does / why we need it: Allows use of DataCite test DOIs with the various import/migrate API calls

Which issue(s) this PR closes:

Closes #8028

Special notes for your reviewer: Does anyone know if the :import and :importddi API calls are intended to allow import of DOIs that don't have the right authority/shoulder to be managed by the Dataverse instance? If not, this PR could be simplified to just check, using credentials, whether the PID exists.

Suggestions on how to test this: Should be able to repeat the migrate tests with a test DOI now

Does this PR introduce a user interface change? If mockups are available, please link/include them here: no

Is there a release notes update needed for this change?: no

Additional documentation:none

[coveralls]

Coverage decreased (-0.001%) to 19.126% when pulling 173fc83 on GlobalDataverseCommunityConsortium:IQSS/8028-enable_import_with_test_DOIs into 1c3dbe8 on IQSS:develop.

[landreev]

Does anyone know if the :import and :importddi API calls are intended to allow import of DOIs that don't have the right authority/shoulder to be managed by the Dataverse instance?

I'm not sure what the original design rationale was. But having thought about it - this sounds like a legitimate use case/scenario. Maybe when somebody needs to be able to import datasets that are under their legacy authority? Or to absorb datasets from another installation (the "how do I merge two Dataverse installations" question we occasionally get).

So this was most likely the reason for that GET attempt in the original code, instead of .alreadyExists(). We could ask - but I'm inclined to just approve the PR as is.

[landreev]

Approving.