Resolve "Job Failed #56264107 and #56261601"

What does this MR do?

Fixes the following broken specs:

• ee/spec/lib/ee/gitlab/ci/pipeline/chain/remove_unwanted_chat_jobs_spec.rb
• ee/spec/workers/build_finished_worker_spec.rb

Why was this MR needed?

remove_unwanted_chat_jobs_spec failures were a consequence of changing external support from Premium to Starter (see https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/4841).

We need to use a project with a repository, since EE::Gitlab::Ci::Config depends on a project with a commit history (it looks for a SHA for fetching external files)

Does this MR meet the acceptance criteria?

• Tests added for this feature/bug
• Review
  • Has been reviewed by Backend
• Conform by the merge request performance guides
• Conform by the style guides
• Squashed related commits together
• End-to-end tests pass (package-qa manual pipeline job)

What are the relevant issue numbers?

Closes #5171 (closed)

Note

Failure is present in master too: https://gitlab.com/gitlab-org/gitlab-ee/commit/f6a35a3cde08d34cbe72dccb8fb3ed58f440f8bd