Add 'chunks' as explicit argument in DROP

[silviacaprioli]

PR description:

As per title

Issues closed by this pull request:

Close #2681

People involved:

Tag here relevant people to involve in the discussion:

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• Tests are included if a new feature is included.
• Documentation is included if a new feature is included.
• Docstrings are updated if needed.
• Changelog is updated.
• Notebooks which requires changes are updated.
• Run Cross check tests for AQUA-diagnostics AQUA-diagnostics cross-check workflow
• environment.yml and pyproject.toml are updated if needed, together with the lumi installation tool. Installation instructions are updated if new conda dependencies are added.