Fix spec violations for internal_ids cross-modification

What does this MR do and why?

At present all the spec violations we found are false positives caused by the fact that ensure_project_iid! is not called on the pipeline before saving. We can remove many of them by just doing this in the after(:build) for the ci_pipeline factory. Others we need to change how the object is constructed in the test setup.

There are still a couple in atomic_internal_id_shared_examples but these are specs that are explicitly trying to do things in transactions and rolling things back so they aren't really representative of real application code so it seemed easier to just wrap these in allow_... for now and extract an issue if we ever want to actually refactor these tests. It may be tricky to refactor them because they are used for other models where these transaction behaviours being tested do indeed matter.

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Related to #335814 (closed)