<!--IssueSummary start--> <details> <summary> Everyone can contribute. [Help move this issue forward](https://handbook.gitlab.com/handbook/marketing/developer-relations/contributor-success/community-contributors-workflows/#contributor-links) while earning points, leveling up and collecting rewards. </summary> - [Close this issue](https://contributors.gitlab.com/manage-issue?action=close&projectId=278964&issueIid=503883) </details> <!--IssueSummary end--> Importers are using different approaches to test if placeholder user references were pushed. We should standardize the approach and preferably use the [Import::UserMappingHelper](https://gitlab.com/gitlab-org/gitlab/-/blob/a91e368eda906028cdaf2904ad6c694410a6b447/spec/support/helpers/import/user_mapping_helper.rb#L5) helper which doesn't rely on stubs.