Add tests for user_group_distinguished_names()

In https://github.com/stackabletech/opa-operator/pull/622#top we added an Active Directory backend to the user info fetcher.

As part of this, there was fairly extensive code to convert between some weird representations which AD chose for userids and groupids.

In order to not block the release with this we decided to punt on adding unit tests (hopefully, worst case: integration tests) for this later.

We should try and get this done fairly soon after 24.11.

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• Describe the use-case, as far is possible. For instance, using the pattern "As a XXXX, I would like XXXX to be able to do XXXX" helps to identify the feature as well as the problem it is intended to address.
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Bắt đầu với mã triển khai và chuyển đổi được thêm trong pull request 622, đặc biệt là đường dẫn user_group_distinguished_names(). Thêm các bài kiểm thử đơn vị hoặc, nếu cần, các bài kiểm thử tích hợp, bao quát các biểu diễn ID người dùng và nhóm của Active Directory; được coi là hoàn thành khi hành vi chuyển đổi được kiểm thử mà không chặn release.