Fix GitLab Duo seeder not working in development env

What does this MR do and why?

This MR fixes that the Duo seeder emits the following error in Evaluation Runner:

Errno::ENOENT: No such file or directory @ rb_sysopen - /home/ubuntu/gitlab-development-kit/gitlab/tmp/tests/gitlab-test.bundle

https://console.cloud.google.com/logs/query;query=resource.labels.instance_id%3D%221831073646643482414%22%0A;cursorTimestamp=2024-12-27T05:11:43.205194361Z;duration=P2D?project=dev-ai-research-0e2f8974&inv=1&invt=AblNuQ

This is because the Git bundle file is not created in development environment by default. This MR switches to a custom repository for fixing this issue and grater flexibility (e.g. we can modify the repository for AI evaluation specific purpose).

This bug is currently blocking https://gitlab.com/gitlab-org/modelops/ai-model-validation-and-research/ai-evaluation/evaluation-runner/-/merge_requests/22+ and https://gitlab.com/gitlab-org/modelops/ai-model-validation-and-research/ai-evaluation/datasets/-/issues/4+.

Confirmed it's working in my GDK:

To run the seeder, execute SEED_GITLAB_DUO=1 FILTER=gitlab_duo bundle exec rake db:seed_fu. See https://docs.gitlab.com/ee/development/ai_features/index.html#seed-project-and-group-resources-for-testing-and-evaluation for more information.

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