Consistent "Close old findings" between UI and API

[fopina]

Description

If we look at the import scan result screen in the UI:

If we look at the API description for the same fields:

I found this confusing the first time I saw and it made me check the code to make sure they were setting the same fields (and they are).

This PR tries to put them in sync, by rephrasing the ones in the UI (as those seem the furthest from the actual variable intent).

I think it could be done the other way around or even switching the field to choices field (Do not close, Close at engagement level, Close at product level) but those would impact API consumers...

Checklist

This checklist is for your information.

• Make sure to rebase your PR against the very latest dev.
• Features/Changes should be submitted against the dev.
• Bugfixes should be submitted against the bugfix branch.
• Give a meaningful name to your PR, as it may end up being used in the release notes.
• Your code is flake8 compliant.
• Your code is python 3.11 compliant.
• If this is a new feature and not a bug fix, you've included the proper documentation in the docs at https://github.com/DefectDojo/django-DefectDojo/tree/dev/docs as part of this PR.
• Model changes must include the necessary migrations in the dojo/db_migrations folder.
• Add applicable tests to the unit tests.
• Add the proper label to categorize your PR.

[dryrunsecurity]

🔴 Risk threshold exceeded.

This pull request contains a sensitive edit to the file "dojo/forms.py" which requires configuration in the .dryrunsecurity.yaml file, but is currently not blocking the pull request.

🔴 Configured Codepaths Edit in dojo/forms.py

Vulnerability	Configured Codepaths Edit
Description	Sensitive edits detected for this file. Sensitive file paths and allowed authors can be configured in .dryrunsecurity.yaml.

We've notified @mtesauro.

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All finding details can be found in the DryRun Security Dashboard.

[mtesauro]

Approved