Input Level API overwrites existing displayOnCreate settings

[Saixel]

What steps does it take to reproduce the issue?

1. Set displayOnCreate to true for a metadata field at input level using the API, e.g., geographicUnit.
2. Confirm that the field appears when creating a dataset in the collection (as expected).
3. Use the same API endpoint to update a different field (e.g., geographicCoverage) without including the previous field (geographicUnit) in the new request.
4. The first field (geographicUnit) is no longer shown during dataset creation.

When does this issue occur?
When updating input level settings for metadata fields using the API.

Which page(s) does it occur on?
During dataset creation, the affected fields are no longer visible.

What happens?
Only the fields specified in the last API call retain the displayOnCreate configuration. Any fields previously configured are reset unless they are explicitly included in the current request.

To whom does it occur (all users, curators, superusers)?
All users creating datasets in the collection.

What did you expect to happen?
Expected the API to only update the fields explicitly passed in the request and preserve any previous displayOnCreate settings unless overridden.

Which version of Dataverse are you using?
v6.6

Any related open or closed issues to this bug report?
New feature introduced in #11224, #11312 and #11343

Are you thinking about creating a pull request for this issue?
Yes, this is something I plan to fix.