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.

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.