Deaccessioned datasets don't get a doi status change from "findable" to "registered" in DataCite

What steps does it take to reproduce the issue?

• When does this issue occur?
  When deaccessioning all versions of a dataset that was published with a doi.

• Which page(s) does it occurs on?
  It relates kinda to the dataset page. The issue can be seen in DataCite Commons (kinda) or DataCite Fabrica for logged in admins of the DataCite account that provided the doi. In Fabrica, you can clearly see the status of the doi and manually change it. But it should be happening automatically.

• What happens?
  After deaccessioning all versions of a dataset, nothing happens to the status of the doi in DataCite. The status remains "findable".

• What did you expect to happen?
  Normally, the doi of a deaccessioned dataset should get the status "registered" once all versions of that dataset are deaccessioned. This ensure the doi still works and leads to the Dataverse thombstone page, but is no longer showing up in search results in DataCite Commons or any system using DataCite Commons as a source (e.g. OpenAire)

Which version of Dataverse are you using?
6.5

Any related open or closed issues to this bug report?

Are you thinking about creating a pull request for this issue?
Not sure where to start

No file or test is named. Start by reproducing deaccessioning every version of a DOI-backed dataset in Dataverse 6.5, then trace the deaccessioning flow and its DataCite update integration. Done means the DOI changes from "findable" to "registered" only after all dataset versions are deaccessioned, while still resolving to the Dataverse tombstone page.