[BUG] Investigate diff issues in production

When enabling the feature flag jupyter_clean_diffs on local, dev and staging, the diffs generated by the code added in #341825 (closed) work as expected. However, in production, for some commits they are either generated partially or not generated at all.

Diff working on staging: https://staging.gitlab.com/eduardobonet/ipynb-diff-test/-/commit/542d42a0196e2e94a0d5793acdee5ba997ab12bf

MR Diff working on staging: https://staging.gitlab.com/eduardobonet/ipynb-diff-test/-/merge_requests/1/diffs

Not working on production: gitlab-org/incubation-engineering/mlops/ipynb-test-projects/diff-sample@542d42a0

Example of diff that should use new code but isn't: gitlab-org/incubation-engineering/mlops/ipynb-test-projects/diff-sample!2 (diffs)